Linear Equations

Question

The sum of two numbers is 138. One number is 20 less than the other. Find the numbers.

Answer 1

x + y = 138 --> equation 1

x - y = 20 --> equation 2

add the two equations, then

2x = 158

x = 158/2 = 79

substitute for x in equation 2, then

79 - y = 20

y = 59

the numbers are 79 and 59