Answer: The required percentage of tip is 15%.
Step-by-step explanation: Given that Sean’s dad paid $41.40 on a meal that cost $36.
We are to find the percentage of tip that he paid.
The amount of tip is equal to the amount paid minus the cost of the meal.
So, the amount of the tip will be

Therefore, the percentage of the tip is given by

Thus, the required percentage of tip is 15%.