Corinne has a job selling magazines. she earns $7.50 per hour plus 20% of the total amount of her sales. she also gets an allowance of $40 per week for gas. she knows her weekly earnings can be shown using the following expression:

7.50h + 0.20s + 40

part a: identify a coefficient, a variable, and a constant in this expression.

part b: if corinne works for 25 hours and sells $300 in magazines, how much does she earn for the week?

part c: if corinne gets a raise and begins earning $9 per hour, would the coefficient, variable, or constant in the equation change? why?