Two cars travel westward along a straight highway, one at a constant velocity of 67 km/h, and the other at a c

Two cars travel westward along a straight highway, one at a constant velocity of 67 km/h, and the other at a constant velocity of 118 km/h.

(a) Assuming that both cars start at the same point, how much sooner does the faster car arrive at a destination 34 km away?
.219 h
(b) How far must the cars travel for the faster car to arrive 20 min before the slower car?
km
i got A but i can't figure out part B.
please helpp

call the distance D

then for each car, we have

D = 67 t (slower car)

D= 118 (t-1/3) (faster car) (since we are using km and hr as our units, t must be expressed in hours, and 20 mins is 1/3 hour)

since the distances are the same, we have

67t = 118(t-1/3)
67t = 118t - 39.33

t=0.77hrs

go back to D=67t and find D=67 km/hr *0.77hr = 51.7 km

Ghg