Rena used the steps below to evaluate the expression , when . step 1: substitute into the expression. step 2: simplify the parentheses. step 3: evaluate the power to a power. step 4: use reciprocals and find the value. in which step did rena make the first error?

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?