BIDMAS question - what's the right answer

[Overstating]

7-5+6x13?

Thanks!

80

80

Another 'vote' for 80.

I'm going to have to go and talk to the teacher aren't I. I thought 80. DC thought -73. The teacher has confirmed -73. There are no brackets around the (5+6x13) but apparently in BIDMAS, the addition has to be done before the subtraction Gaaah!

Teacher is wrong. The answer is 80. I have no clue what BIDMAS is (way after my time) but it doesn't change the answer.

Multiplication is done first so 6x13=78

Addition and subtraction are equal priority so it's left to right.
7-5 = 2
2+78 = 80

Oh I thought 80 too.

7-5 then 6x13 then add the two figures together

6x13 needs to be done first = 78. The + and - are of equal importance so you just follow the operation from left to right.

7-5+6×13 = 7-5 +78
2+78= 80

Doing subtraction then addition gives the same answer btw
-5+7+78 = 80

Yeah the teacher is wrong. Addition and subtraction are of equal weighting.

That's definitely wrong. -73 only works as an answer if brackets ensure the whole thing becomes negative.

P.s. the + or - stays with the number so its +7 and -5

Teacher is wrong. (maths degree).

I'd be tempted to write a short note assuming they do know it really but must have had a brain explosion.

Teacher needs to think about totalling the numbers 9, 2, and -3. the total is the same (8) whether you say
9+2-3 to get the total or -3+9+2 or 2-3+9

It's 80. Pretty that a teacher is saying otherwise. Unless BIDMAS is somehow different to BODMAS. I teach maths at HE level.

I dont even understand where -73 comes from. What calculation gives that answer?

80

And it's BODMAS not BIBMAS

Its BIDMAS to some people.

To others its PEMDAS. makes no odds as the answer is 80

What does the I in BIDMAS stand for? I'm only familiar with BODMAS but am open to being told I'm wrong

It's 80. I teach BIDMAS down over so

B
I
D
M
AS

Because add and subtract go left to right

And it's BODMAS not BIBMAS

It’s BIDMAS not BIBMAS.

Which acronym is used depends on the school. It isn’t important.

The answer is 80 and I’m very concerned about a primary school teacher getting this wrong.

The first B/P is brackets/parenthesis
The O/I/E is of/order/index/exponent(?) (things like squared or square root)
Then D/M are equal
and A/S are equal

Because add and subtract go left to right

They absolutely do not have to go left to right. You can do them in either order.

BIMDSA doesn’t make as nice an aide memoir but is equivalent mathematically.

I wish I'd posted in AIBU. I'd be polishing my medal for unanimous response

They absolutely do not have to go left to right. You can do them in either order.

True, but you are more likely to do them left to right once everything else is sorted.

I wish I'd posted in AIBU. I'd be polishing my medal for unanimous response

No you wouldn't.
You'd have had a whole bunch of posters telling you the teacher was right and ignoring the teachers / scientists / maths degree people who were on your side. It has happened before and will happen again.