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

The two numbers are 28 and 36