Please help me with this

Aflute is on sale for 20% off. including the discount and 8% tax, the sales price is $216.

Sophia wrote an equation to represent the revenue of a movie theater for one day. she let x represent the number of child tickets sold and y represents the nunver of adult tickets sold. if a child ticket cost $4, an adult ticket cost $6, and the total revenue for the daybwas $420, which equation could sophia use to represent the number of chikd and adult tickets that were sold?

Geometry - finding area of regular polygons and sectors (check my math, i can’t find the error)