(Rational expression word probelm) A person traveled...

Question

A person traveled 120 km in one direction.  The return trip was made at double the speed and in 3 hours less time.  Find the speed going.

Answer 1

let t be the time taken to travel
let v be the speed
tv = 120
2v(t-3) = 120
v = 120/t
2(120/t)(t - 3) = 120
(240/t)(t - 3) = 120
240 - 720/t = 120
240 - 120 = 720/t
120 = 720t
t = .167
v ≈ 120/.167 = 720 km/hr.