Ankush does 1 round per 20 minutes. Babulal does 1 round per 12 minutes. Then, we have to find in how many minutes it take to complete a round together ⇒
x
20
+
x
12
= 1 ⇒
8x
60
= 1 x = 7.5 min (they meet after every 7.5 min) from 9 am. to 10:30 am they meet ⇒