Answer plz
Test for my lil sis

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 are the solutions of the equation x4 + 6x2 + 5 = 0? use u substitution to solve.

Find the value of x. also give me an explanation so i can complete it to other questions as well, : )