Question 864790
D=RT
FOR THE SPORTS CAR
D=90(T-5)
FOR THE FAMILY CAR
D=50T
90(T-5=50T
90T-450=50T
90T-50T=450
40T=450
T=450/40
T=11.25 HOURS 
PROOF:
D=90(11.25-5)
D=90*6.25
D=562.5 MILES
D=50*11.25
D=562.5 MILES