Question 829395
Two motorist undertake a journey by car.
 One motorist travel at an average speed of 100 km/h and the other travel at an average speed of 120 km/h.
If the faster motorist arrives 1.5 hours earlier hours than the slower motorist, how long did the slower motorist take?
:
Let d = the distance of the journey
Write a time equation; time = dist/speed
:
slow car time - fast car time = 1.5 hrs
{{{d/100}}} - {{{d/120}}} = 1.5
multiply by 600, cancel the denominators
6d - 5d = 600(1.5)
d = 900 km
Find the time of slower car
{{{900/100}}} = 9 hrs
:
:
Check this by finding the time of the faster car
{{{900/120}}} = 7.5 hrs, 1.5 hrs sooner