Help QuickTime I got minus 10 but apparently its wrong

Ineed to know the answer to this algebra question.

Guys i need ! graded assignment grade 8 checkpoint 2, part 2 answer the questions below. when you are finished, submit this assignment to your teacher by the due date for full credit. total score: of 9 points (score for question 1: of 4 points) 1. the cost of renting a car for a day is $0.50 per mile plus a $15 flat fee. (a) write an equation to represent this relationship. let x be the number of miles driven and y be the total cost for the day. (b) what does the graph of this equation form on a coordinate plane? explain. (c) what is the slope and the y-intercept of the graph of the relationship? explain.

Acompany made a profit of 75000 over a period of 6 years on an initial investment of 15000 what is the annual roi