The sum of Juan’s age and Sara’s age is 33 yrs. If Sara is 15 yrs old, how old is Juan?

[math_celebrity]

The sum of Juan’s age and Sara’s age is 33 yrs. If Sara is 15 yrs old, how old is Juan?

Let j be Juan's age and s be Sara's age. We have the following equations:

1. j + s = 33
2. s = 15

Substitute (2) into (1)
j + 15 = 33

Using our equation solver, we get j = 18