How to solve 7+(-15)+12

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?

Ineed the solution to this problem and the steps.

Jonah buys a television that costs $445. sales tax in his state is 7 percent. which of the following expressions represent the amount of tax on the television?