Answer:
The speed of Kali is 30 mph.
Explanation:
Let, the speed of Kali be "x", then speed of Ndiba will be:
Speed of Ndiba = x + 15 mph
If, the time for travel for Ndiba is 2 hrs, when he catches Kali, and he left 1 hour later than Kali, then then time traveled by Kali at that instant will be 2+1 = 3hrs.
At the point of meeting both will have covered same distance.
Distance Covered by Kali = Distance Covered by Ndiba
(Speed of Kali)(Time traveled by Kali) = (Speed of Ndiba)(Time traveled by Ndiba)
(x)(3) = (x +15)(2)
3x = 2x +30
x = 30 mph
The correct answer is, actually 30 mph, by the solution shown above.