Question

Going for a long trip, Thomas drove for 2 hours and had lunch. After lunch he drove for 3 more hours at a speed that is 20 km/hour more than before lunch. The total trip was 460 km.

a) What was his speed after lunch?

Answer 1

100km/h
Take initial speed as x.
Distance travelled = speed * time taken
" = x*2
=2x
Speed after lunch=x+20
Dt=(x+20)*3
=3x+20
Total distance=2x+3x+60
5x=400
x=80
X+20=100

Answer 2

Let the speed before lunch be x
So, speed after lunch = x + 20

Distance traveled before lunch = 2x
Distance teablled after lunch = 3(x+20) = 3x + 60

2x + 3x + 60 = 460
5x = 400
x = 80 km/hr

Speed after lunch = x + 20 = 80 + 20 = 100 km/hr