Help with 4 and 5 plz

Translate the word phrase into a math expression. 15 fewer than the product of 4 and a number. (pls immediately)

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.

Consider the sequence below. 3 , 1 , 1/3 , 1/9 , select the explicit function which defines the sequence.