Help with this please it's a test

At noon a tank contained 10cm water. after several hours it contained 7cm of water. what is the percent decrease of water in the tank?

Lucy is a dress maker. she sews \dfrac47 7 4 ? of a dress in \dfrac34 4 3 ? hour. lucy sews at a constant rate. at this rate, how many dresses does lucy sew in one hour? include fractions of dresses if applicable.

After several softball games, jenni has 12 hits and 5 walks.what is the ratio of hits to walks