George vacuums the rugs every 21 days, mows the grass every 12 days, and pays the bills every 15 days. Today he did all three. How long will it be before he has another day like today?

LCM(21,12,15) = 2^2*3*5*7 = 420

Steve is right...

its 84 sec

sorry that was for another question

Ann and Bob are cycling on a track. Ann completes one lap every 12 seconds, and Bob completes one lap every 21 seconds. After how many seconds will Ann and Bob reach the finish line at the same time, assuming that they started together?

To find out when George will have another day like today, we need to find the least common multiple (LCM) of the three intervals: 21 days, 12 days, and 15 days.

First, let's find the LCM of 21 and 12 days:

Multiples of 21 days: 21, 42, 63, 84, ...
Multiples of 12 days: 12, 24, 36, 48, ...

By examining the multiples, we can see that the LCM of 21 and 12 days is 84 days, as it is the smallest number that is both a multiple of 21 and 12.

Next, let's find the LCM of 84 days and 15 days:

Multiples of 84 days: 84, 168, 252, ...
Multiples of 15 days: 15, 30, 45, 60, ...

The LCM of 84 days and 15 days is 420 days as it is the smallest number that is both a multiple of 84 and 15.

Therefore, George will have another day like today after 420 days.

You are both wrong

Steve you are wrong! its 315