Can y’all help me answer the questions pls

Solve: 3x+y=6 4x-2y=18 show all work !

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.

For the following geometric sequence, find the recursive formula. {-80, 20, -5, } i need : ')