Physic problem?

Question

Two cars travel westward along a straight highway, one at a constant velocity of 87 km/h and the other at a constant velocity of 113km/h.
A) assuming that both cars start at the same point, how much sooner does the faster car arrive at a destination 16 km away?
B) How far must the cars travel for the faster car to arrive 20 min before the slower car?
i've done the part A but stuck at the B one, so plz help me w/ the part b

Answer 1

A)
for fast car
16=113*tf
for the slow car
16=87*ts

ts-tf=16*(1/87-1/113) *60 minutes
2.54 minutes

B)
for the fast car
d=113*tf
for the slow car
d=87*ts
ts-tf=20 min
20=d*(1/87-1/113)*60
solve for d
d=126 km

j