Who here can help me on an 8th grade quiz? its for math btw

Asap 25 pts + brainlest to right/best answer

What is the axis of symmetry of the function f(x)=-(x+ 9)(x-21)

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? $$