One number is four times another number. If their sum is 95, what are the numbers?
Let x be one number and y be the other.
#1 - Set up a system of equations.
4x = y
x + y = 45
#2 - Solve the system by substitution.
x + (4x) = 45
5x = 45
x = 9
(9) + y = 45
y = 36
The numbers are 19 and 76.