Which expression is equivalent to the expression 6(-2n + 7) - 3(5n + 9)?

Julie goes to the sports store and spends $40.50 before tax. she buys a pair of shorts for $21.75 and 3 pairs of socks that each cost the same amount. how much does each pair of socks cost? $$

What is the sum of the first 8 terms of the geometric series

What’s the answer? and how do i solve it ?