Answer:
1 round = 15 laps
? round = 30 laps
30 / 15 × 1 = 2 rounds
Find the multiples of each number:
18: 1 , 2 , 3 , 6 , 9 , 18
24: 1, 2, 3, 4, 6 , 8, 12, 24
Now find the matching numbers:
1 , 2, 3 , 6