Let x represent the first number
Let y represent the second number
x + y = 18
x - y = 4
Use elimination method to solve this system of equations:
2x = 22
x = 11
Plug the x-value into one of the original equations to solve for y:
x - y = 4
(11) - y = 4
y = 7
The two numbers are 7 and 11