Step 1. Calculate 15% of the meals served.
Since he served $725 worth of meals, we calculate 15% of $725. We do this by dividing 725 by 100 and then multiplying by 15:
He earned $108.75 on tips.
Step 2. Add the tips to the amount he earns each weekend.
He earns $80 each weekend plus the tips:
Answer: $188.75