Question

If 5x and 9y =28 and x and y are positive integers what is the value of x?

Answer 1

I interpret 5x and 9y =28 as
5x + 9y = 25

since x and y must be positive integers,
5x could only have values of 5, 10, 15, 20, 25
9y could only have values of 9, 18, 27

now what number from the first set added to a number of the second set yields a sum of 28 ?

Answer 2

10 and 18

Answer 3

So x=2?

Answer 4

clearly, yes