Solve using substitution

Question

The difference of two numbers is 7

their sum is 145

find the numbers

Answer 1

x - y = 7

x + y = 145

In the first equation, add y to both sides to get x = y + 7.

(y + 7) + y = 145

2y + 7 = 145

2y = 138

y = 69

x + 69 = 145

x = 76

The two numbers are 69 and 76.