A window cleaner has enough supplies to clean 21 windows per office building on a certain number of buildings. They can also clean the windows of a school with 42 windows. Altogether, there are

Answer 1

21 windows per office building and there are a certain number of buildings, so the total number of office windows cleaned is 21 * number of buildings
The total number of windows cleaned is 21 * number of buildings + 42 windows for the school
21 * number of buildings + 42 = total windows cleaned. Answer: \boxed{21 \cdot \text{number of buildings} + 42}.