Question

Asanji left the science museum and drove toward the lake at an average speed of 45 km/h. Sometime later Huong left driving in the same direction but at an average speed of 75 km/h. After driving for three hours Huong caught up with Asanji. How long did Asanji drive before Huong caught up?

Answer 1

Asanji drove for
`5` hours before Huong caught up

Explanation:

Let the time for which Asanji drove alone is "X" hours

Asanji and Huong met after three hours of driving of Huong.

Total time for which Asanji drove
`= X+3` hours

Thus, distance travelled by Asanji in
`X+3` hours is equal to distance travelled by Huong in
`3` hours

`45 ( X+3) = 75 (3)\\`

On solving the above equation, we get -

`45 X + (45 *3) = 75 *3\\45 X = (75-45)*3\\45 X = 30 *3 \\X = (30 *3)/(45) \\X = 2`

Asanji drove for
`3 + 2 = 5` hours before Huong caught up