What does it mean if a negative number was in perentices while using exponents

Aiden drives to school and back each day. the school is 16 miles from his home. he averages 40 miles per hour on his way to school. if his trip takes 1 hour, at approximately what speed does aiden drive home?

The number of fish in a lake can be modeled by the exponential regression equation y=14.08 x 2.08^x where x represents the year

An investment decreases in value by 30% in the first year and decreases by 40% in the second year. what is the percent decrease in percentage in the investment after two years