The sum of two numbers is 64. one number is 8 more than the other. what are the two numbers?

Write an equation system related to the problem
eg. a and b are the numbers
An equation for "The sum of two numbers is 64" is
⇒ a + b = 64
An equation for "One number is 8 more than the other" is
⇒ a = b + 8

Solve the equation system by subtitution method
Subtitute a with b + 8 in the first equation
a + b = 64
(b + 8) + b = 64
2b + 8 = 64
2b = 64 - 8
2b = 56
  b = 28
The first number is 28

Subtitute the value of b to the second equation
a = b + 8
a = 28 + 8
a = 36

The two numbers are 28 and 36