SOLUTION: Twice last month, Judy Carter rented a car in Fresno, California, and traveled around the Southwest on business. The car rental agency rents its cars for a daily fee, plus
Question 1136671: Twice last month, Judy Carter rented a car in Fresno, California, and traveled around the Southwest on business. The car rental agency rents its cars for a daily fee, plus an additional charge per mile driven. Judy recalls that her first trip lasted 4 days, she drove 390 miles, and the rental cost her $260.50. On her second business trip she drove 190 miles in 3 days, and paid $159.50 for the rental. Find the daily fee and the mileage charge. Answer by ikleyn(52786) (Show Source):
Let x be daily fee and y be additional charge per mile.
Then from the condition we have this system of 2 equations in 2 unknowns
4x + 390y = 260.50 dollars (1)
3x + 190y = 159.50 dollars (2)
Now I apply the determinant method (the Cramer's rule) :
1) d = determinant of the coefficient matrix = 4*190 - 3*390 = -410;
2) x = = 31;
3) y = = 0.35.
ANSWER. Daily fee is $31; Mileage charge is $0.35 per mile.
