The difference of two numbers is 18, and their sum is 90. Find the two numbers.

Question

The answer Im looking for is not substitution. Im looking for an answer with only one variable.

Answer 1

x and x+18 are the numbers

x+(x+18)=90

2x+18=90

2x=72

x=36

x+18=54

36 and 54 are the numbers