Please help with 5-7

The swimming pool is open when the high temperature is higher than 20∘c. lainey tried to swim on monday and thursday (which was 3 days later). the pool was open on monday, but it was closed on thursday. the high temperature was 30∘c on monday, but decreased at a constant rate in the next 3 days. write an inequality to determine the rate of temperature decrease in degrees celsius per day, d, from monday to thursday.

Bo is buying a board game that usually costs bb dollars. the game is on sale, and the price has been reduced by 18\%18%. what could you find the answer?

What percent of 18 is 24? and plz explain thx.