How do I solve these Calculus problems, all questions and all parts?

Plzzzz i beg u asap ! what is the equation of this graphed line? enter your answer in slope-intercept form in the box.

The sales tax rate is 7.25%. how much tax in dollars is added on an item that costs $56.00? a. $4.06 b. $7.25 c. $14.50 d. $60.06

How many credit hours will a student have to take for the two tuition costs to be equal? round the answer to the nearest tenth of an hour.