Amar, Akbar and Anthony are playing a game. Amar climbs 5 stairs and gets down 2 stairs in one turn. Akbar goes up by 7 stairs and comes down by 2 stairs every time. Anthony goes 10 stairs up and 3 stairs down each time. Doing this they have to reach to the nearest point of 100th stairs and they will stop once they find it impossible to go forward. (They have less number of stairs than required forward stairs).
What is the first stair where any two out of three will meet together?

Options

A. Amar and Akbar will meet for the first time after 15 steps.
B. Akbar and Anthony will meet for the first time after 35 steps.
C. Amar and Anthony will meet for the first time after 21 steps.
D. Amar and Akbar will meet for the first time after 21 steps.

Answer

A

Explanation

Since LCM(3, 5)=15 , LCM(5, 7)=35 , LCM(3, 7)=21. Since, 15 is the smallest so Amar and Akbar will meet for the first time after 15 steps.
Thus (a) is correct option.