True or false: tangent line approximation works at any point on any graph.

Answer pls man im trying to get out of summer school

Ijust need these 2 questions answered (the second pic is just confirmation i'm not confident in that answer)

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?