What is the formula for a finite geometric series and how can you use it in a practical situation?

Easy points boii. read it. ya. fresh

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? $$

Given δjkl : δxyz, find x. a)10 b)12 c)16 d)20