What are the coordinates of the point on the directed line segment from (-5, -4)(−5,−4) to (9, 8)(9,8) that partitions the segment into a ratio of 3 to 1?

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? $$