A car travels 560 mi averaging a certain speed. If the car had gone 10 mph​ faster, the trip would have taken 1 hr less. Find the​ car's average speed. The speed is

Answer 1

560 = rt distance = rate of speed times time, d=rt

560 = (r+10)(t-1) = rt + 10t -r -10

subtract 1st equation from 2nd

0= 10t-r-10

r =10t -10

560= rt = (10t-10)(t

10t^2 -10t -560 = 0

t^2 -t -56 =0

(t-7)(t-8) = 0

t = 7 or 8

560/7 = 80 mph

560/8 = 70 mph

Had the car gone 10 mph faster than 70 mph , it would have arrived 1 hour earlier