Anew clothing store is offering 30 free points to customers who sign up for their rewards card. then for each shirt a customer buys, they earn an additional number of points. mr. smith signs up for the rewards card and purchases 3 shirts. he earns 75 points.

how many additional points does a customer earn on purchasing one shirt?

write an equation that represents the relationship between the number of shirts purchased, n , and the total number of points earned, p .