Tom and Jerry took part in a race. Both boys started running at the same time. After 4 hours, Tom had completed the race but Jerry had covered only 4/5 of the route. If Jerry's average speed was 2km/h less than Tom's, find the length of the route.

Answer 1

distance = speed * time, so if Tom's speed is s, his distance was 4s. For Jerry,

(4/5)(4s) = 4(s-2)

solve for s, and then you can get the distance: 4s

Answer 2

Tom's speed = X km/h.
Jerry's speed = x-2 km/h.
Tom: d = x * t. = 4x.

Jerry: 4d/5 = (x-2)*t
d = (1.25x - 2.5)t
d = (1.25x - 2.5)4
d = 5x - 10.

d = 4x = 5x - 10
4x = 5x - 10
X = 10 km/h.

d = 10km/h * 4h = 40 km. = Length of the route.