Question

a bus arrives at a stop every 12 minutes. another bus arrives at the same stop every 15 minutes. if both buses arrive at the same time now, after how many minutes will they arrive together again?

Explanation:

Step1: Prime factorize 12

$12 = 2^2 \times 3$

Step2: Prime factorize 15

$15 = 3 \times 5$

Step3: Find LCM of 12 and 15

Take highest powers of all primes: $2^2 \times 3 \times 5 = 4 \times 3 \times 5$

Answer:

60