School guidelines require that there must be at least 2 chaperones for every 25 students going on a school trip. How many chaperones must there be for 80 students?

Nadia traveled by bike at an average speed of 9 miles per hour.
Then, she traveled by car at an average speed of 32 miles per hour.
In total, she traveled 28 miles for 1 hour.
How many minutes did Nadia travel by car? (Round to the nearest minute.)

Starting at home, Jessica traveled uphill to the gift store for 36 minutes at just 10 mph. She then traveled back home along the same path downhill at a speed of 30 mph.
What is her average speed for the entire trip from home to the gift store and back?