A(n)=12+(n-1)(5) find the fourth, sixth, and thirteenth terms

Ernest is purchasing a $175,000 home with a 30-year mortgage. he will make a $15,000 down payment. use the table below to find his monthly pmi payment.

Sasha drank 8 bottles of water everyday for a week. how many bottles of water did she drink in total?

What is the answer to this question? i'm a bit stumped. also how do i do it? 5(x - 4) = 2(x + 5)