Sam is 52 years old. This is 20 years less than 3 times the age of John. How old is John

Sam is 52 years old. This is 20 years less than 3 times the age of John. How old is John

Let John's age be j. We're given the following equation:
3j - 20 = 52 (Less than means we subtract)

To solve for j, we type this equation into our search engine and we get:
j = 24