Given the Arithmetic Sequence 9,12,15,18,21,...find the formula 1. A(n)=3+(n-1)9
2. A(n)=9+(n-1)3
3. A(n)=21+(n-1)9
4. A(n)=9+(n-1)21

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.