Maths question help please?

[Lucyccfc]

I'm thinking of a secret number. I multiply it by 10. I also multiply it by 5.
When I add the two answers I get 165. What is my secret number?

Got a complete mental block in how to work this out?

Thanks

I think it's 11. I came to this conclusion by dividing 165 by 15 (which is the 10 and the 5 added together). I could be wrong. It's been a long day already.

Yes, you are adding 10 lots of the number to 5 lots of the number, so you have 15 lots. Divide 165 by 15 and you get 11.

10x+ 5x= 165
15x=165
X= 165/15
X= 11

Assuming X is the number you are looking for

10x + 5x = 165 (this is what the question is telling us)
15x = 165
(pass the 15 over to the other side)
x = 165/15
x = 11

cross post!

Thank you both.

That's the way I was showing my son to do it, but he wasn't listening and wanting to divide by 10 and 5 separately, but it wasn't working.

Your help was much appreciated.