3.91x10^-2 in standard form

Haruka hiked several kilometers in the morning. she hiked only 66 kilometers in the afternoon, which was 25% less than she had hiked in the morning. how many kilometers did haruka hike in all?

What is the greatest number of parts of a circle that can be formed by cutting the circle with 7 straight cuts? (note: the parts do not have to be equal in size)

Tessa bought stock in a restaurant for $253.00. her stock is now worth $333.96. what is the percentage increase of the value of tessa's stock? a.) 81% b.) 32% c.) 24% d.) 76%