im super stuck on this qestion

Question

the sum of two numbers is 15 and the diffrence is 7

Answer 1

Let "x" be one number and let "y" be the other number.

Then "the sum of two numbers is 15" means x + y = 15

And "the difference of two numbers is 7" means x - y = 7 or x = y + 7. Now, replace "x" in the first equation with "y + 7" because they are both the same:

x + y = 15

(y + 7) + y = 15

y + 7 + y = 15

2y + 7 = 15

2y = 8

y = 4

Since x = y + 7, then x = 4 + 7 or x = 11

So the two numbers are 4 and 11