Write a system of equation based on the number
For an instance, the two numbers are a and b.
"The sum of two numbers is 59" can be written as follows.
⇒ a + b = 59 (first equation)
"The difference is 15" can be written as follows.
⇒ a - b = 15 (second equation)
Solve the system of equation by elimination/substitution method.
First, eliminate b to find the value of a.
a + b = 59
a - b = 15
--------------- + (add)
2a = 74
a = 74/2
a = 37
Second, substitute 37 as a in one of the equations
a + b = 59
37 + b = 59
b = 59 - 37
b = 22
The numbers are 37 and 22