Question

If x and y are positive integers, and 3x+2y=21, what is the sum of all possible values of x?

Answer 1

What is y when x = 1?

Answer 2

9

Answer 3

Do you know why we shouldn't start with x = 0?

Answer 4

because it is not a positive integer

Answer 5

Well, what about x = 2? Will that work for this?

Answer 6

No?

Answer 7

Why not?

Answer 8

i couldnt find a number that works for both

Answer 9

It's because if x = 2, then y won't be an integer.

Answer 10

ya true

Answer 11

So just continue from there until you collect all the possible x values that work, then add them up.

Answer 12

ok thanks can you tell me the answer so I can check if I get the right answer

Answer 13

It's better if you tell me what you think the answer is, then I'll let you know if it's correct or not.

Answer 14

ok so is 9 the answer because 1+3+5?

Answer 15

because 7 doesn't work because you would have to put 0 which is not a positive integer

Answer 16

Congrats

Answer 17

thanks!

Answer 18

You're welcome