you lift weights every third day and swim every fourth day. If you do both activities today in how many days will you do both activities on the same day again

Question

I need help on an old problem that stumped me while growing up and having kids

Answer 1

The answer is the least common multiple of the two numbers - 12.

After the fourth cycle of lifting weights it shall be the twelfth day.

After the third cycle of swimming it shall also be the twelfth day.