A golfer rides in a golf cart at an average speed of 3.10 m/s for 21.0 s.
she then gets out of the cart and starts walking at an average speed of
1.40 m/s. for how long (in seconds) must she walk if her average speed
for the entire trip, riding and walking, is 2.40 m/s?
-------------------------
avgespeed = total distance/total time
golf cart ...tot dist = 3.1x21.0
walking ...
1.4 = distance/time
combined ...
(3.1x21.0+1.4xt)/(21+t2)=2.4
solve for t2 => 0.7x21
