Dana is riding her bike. She rides 20 miles in 2 hours, 30 miles in 3 hours, and 40 miles in 4 hours. Find the constant of proportionality and write an equation to describe

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? $$