A truck company charges $30 to rent a moving truck for the day, plus 5 cents for every mile driven during the day. The function f(x)=0.05x+30 represents the total cost for the moving truck for one day's rental where x is the number of miles driven.
Part A: Jada rents the moving truck for one day and drives a total of 42 miles. What would be her costs for the rental?
Part B: Kimmy rented the same moving truck and spent a total of $37.80. How many miles did she drive during the rental period?