a fireplace contains 54 bricks along its bottom row. if each row above decreases by 3 bricks, what is the function that shows the bricks on the 10th row

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? $$