A plane flew from Smithtown to Johnsville and back. The duration of the trip there was 1 hour less than the duration of the trip back. The average speed on the trip there was 240 mph. The average speed on the trip back was 220 mph. How many hours did the trip take?

Mia spent 30 minutes answering the math questions on the exam. this was 1/4 of the total amount of time allotted for this section of the exam. to determine the total amount of time allotted for this section of the exam, mia set up and solved the equation as shown below. which best describes the error that mia made when solving the equation?