Question

17 A tourist was planning a trip by car for travelling at some constant speed for 2.5 hours. However, he found that if he increases the speed by 20 km/h he can cover the same distance in 30 minutes less time than it was planned. What was the planned speed of the tourist, in km/h?

Answer 1

Amount of time=2.5 hours
Amount of time after speed increase=2 hours
Let x=the initial speed
Let t=the amount of hours
Let y=the new speed
Let z=distance

Therefore XT=z
YT=z

Plugging everything in,
X(2.5)=z
Y(2)=z

Using substitution
Y=20+x


2.5x=z
(20+x)(2)=z

40+2x

.5x=40
X=80
Y=x+20
Y=100