A coach is travelling from Town D to Town E. At 75 km/h, it will arrive four hours later than the scheduled time. At 90 km/h, it will arrive at two hours later than the scheduled time. What is the distance between Town D and Town E?
| |
Faster speed |
Slower speed |
| Speed |
90 km/h |
75 km/h |
| Time |
1 u + 2 |
1 u + 4 |
| Distance |
90 (1 u + 2) =
90 u + 180 |
75 (1 u + 4) =
75 u + 300 |
Distance covered for the faster speed or the slower speed is the same.
90 u + 180 = 75 u + 300
90 u - 75 u = 300 - 180
15 u = 120
1 u = 120 ÷ 15 = 8
Distance between Town D and Town E
= 90 u + 180
= 90 x 8 + 180
= 720 + 180
= 900 km
Answer(s): 900 km
