To think that this sum is super simple

[PeerieBreeks]

and can't understand how so many people on Facebook have it so completely wrong (and can justify it to themselves).

Without adding your reasoning, tell me what you think the answer is.

frankchickens, I'm not smug I promise, and I'm sorry that I must have come across that way as you are the second person to say it.

Nobody on this thread has come anything close to saying the kind of things that was said on Facebook that prompted me to post this. I have already said I can see why people think it is 10 or 30, and the people that think it is 10 are actually thinking too much into it, not too little.

I promise you there are many, many things I'm rubbish at, that other people find easy. Like keeping houseplants alive for one

Please, Ifailed, don't!

Can we have a BIDMAS question now? 😝

Think of it this way FatBottomedGal

Imagine he starts with $100. He buys a horse for $60 so he has $40 left

Then he sells the horse for $70 so he now has $110

Then he buys a horse for $80 so he's down to $30

Then he sells the horse again for $90 so he now has $120 - that#s 420 more than he started with

Bugger, that $20 more

frankchickens, I'm not smug I promise, and I'm sorry that I must have come across that way as you are the second person to say it.
I meant it in the gentlest way - gentle joshing.
It is interesting though that these sorts of things don't attract the same degree of ire as postings about incorrect grammar or spelling.

It's 20. Surprised how many people are saying 10.

If people would like sell me a horse for £60, buy it back for £70, sell it to me for £80 and buy it back for £90, I'll pay you £15 for doing it.

Abra1de Facebook seems full of those. It's quite frightening how many people clearly slept though most of their maths classes!

(mind you, I did it for French)

People are getting distracted by the change in the value of the horse
The man made two separate sales and he made $10 profit on each sale
$20 total

he's made $20
spends $60 - he's $60 down
sells for $70 - he's up $10
spends $80 - ($10 - $80) = $70 down
sells for $90 - ($90 - $70) he's made $20

First transaction made $10, 2nd transaction lost $10. Overall net gain 0, loss cancels out original gain. Problem I have is where does he get the capital from to buy back at a higher price. He can't really complete the sale but for the sake of the conundrum I'll continue. He buys at 80 sells at 90 makes $10 clear profit at final close of business

He doesn't need to borrow anythig if he started the day with $70. As fer as we know he has not incurred any expenses so net profit is a total irrelevance.

bakingaddict - but you didn't have a problem wondering where we had $60 to make the first purchase?

If you start with say $100 in hand and work it through you end up with $120 at the end. No need to borrow, and definitely $20 profit.

Bakingaddict, no one ever said 'a man has only $60' at the start.
When there were questions at school about 'Jane gave tom 3 sweets, then gives Cedric 2 sweets', no one worried that she didn't have enough sweets to do that! Its the same sort of thing - assume that if he is buying something, he had enough money.

Here is why I thought 10.00 up-
The question was has he made, lost or broken even. He has a horse worth 60 he sells for 70 so is 10 up. Next day he wants the horse back so buys it for 80.00 voiding his 10.00 profit. He sells for 90 making his 10.00 back hence although he made 10.oo twice, he lost 10.00 and is only 10.00 up over all.

To me, it really is unbelievable that such simple arithmetic causes such debate.

A-B+C-D= cannot possibly have any other result.

I hate the "oh I'm terrible at maths" that people say with pride and as if that's that. First of all, this isn't maths, it is arithmetic. Second of all, there is no such thing as a brain which cannot learn maths but can learn all other subjects fine. Sure, perhaps the more complex mathematical equations might be a struggle, but pretty much everyone who is capable of learning to read and write is capable of learning arithmetic.

that#s 420 more than he started with
Wow, I this maths better

So I bought a pair of shoes for $60, and I bought a handbag for $80
I decided I don't like the shoes or the handbag so I put them on eBay
I sold the shoes for $70 and then I sold the handbag for $90
I've made $20
nice one 😁

No, Lois, as has already been explained, you can't use the $70 transaction twice. Once it's been used to derive a $10 profit, you can't then pair that same transaction with the $80 purchase and identify a $10 loss.

Problem I have is where does he get the capital from to buy back at a higher price.

NOWHERE does it state that he only had $60 to start with. He could have had a couple of million dollars to play with.

baking, you are conflating 2 separate issues.

First sale, he ends up with $10.

2nd sale, he ends up with $10.

There is no loss involved in the repurchase of the horse. Besides, he could have renivested that $10 in a donkey meanwhile and is possibly quids up from that too

Hah, $20 profit (140 spent vs 160 taken)

But, I can see how one could arrive at 'break even', if one ignores the first purchase price and only starts calculating profit and loss once he already owns the horse. There is no reason to do that though.

He made a tenner.

But I'm shit at maths anyway so

He has an extra 20 in his hand

But only 10 is profit