Complete question :
Victor left his house riding his bike at a speed of 18 km/h. When Victor was 1/2 km away from his house his brother Alex left the house riding at a rate of 24 km/h. How long will it take Alex to catch up with Victor?
Answer:
0.083333 or 5 minutes
Explanation:
Victor's speed = 18 km/hr
Alex's speed = 24 km/hr
Alex left after Victor has moved a distance of 1/2 km
Time Alex will catch up with Victor :
Let time = x
distance at which Victor = Alex
(18 * x) + 0.5 = (24 * x)
18x + 0.5 = 24x
18x - 24x = - 0.5
-6x = - 0.5
x = 0.5 / 6
x = 0.0833333 hour
x = 0.0833333 *60 = 5 minutes