A washer and a dryer cost $911 combined. The washer costs $39 less than the dryer. What is the cost of the dryer?

Sum and difference problem, where difference = larger number - smaller number.

The larger number is (sum+difference) / 2.

The smaller number is (sum - difference) / 2

Therefore the dryer costs (911+39) / 2=475

The washer costs (911-39) / 2=436