Question 569518
rate of 1st car = x
rate of 2nd car = x + 6
time = 8 hours
distance = 768

rate of 1st car * time + rate of 2nd car * time = distance
x(8) + (x + 6)(8) = 768
8x + 8x + 48 = 768
16x + 48 = 768
16x = 720
16x/16 = 720/16
x = 45

rate of 1st car = 45 mph
rate of 2nd car = x + 6 = 45 + 6 = 51 mph