Answer:
60/15 = 4 hrs
Step-by-step explanation:
1. A motorcycle driver travels 15kph faster than a bicycle rider.
The motorcycle driver covers 60 km in two hours less than the time it takes the bicycle rider to travel the same distance?:
Let s = the bike speed
then
(s+15) = the motorcycle speed
Write a time equation; time = dist/speed
Bike time - M'cycle time = 2hr
60%2Fs - 60%2F%28%28s%2B15%29%29 = 2; Sorry for the mistake here!
multiply eq by s(s+15) cancel the denominators and you have
60(s+15) - 60s = 2s(s+15)
60s + 900 - 60s = 2s^2 30s
Combiner as a quadratic equation on the left
0 = 2s^2 + 30s - 900
simplify divide by 2
s^2 + 15s - 450 = 0
Factors to
(s+30)(s-15) = 0
the positive solution
s = 15 km/hr is the bike speed
then
30 km/hr is M'cycle speed
