Question

Juanita runs every third day and swims every fifth day. If Juanita runs and swims today, in how many days will she run and swim again on the same day?

Answer 1

We are looking for the least common multiple of 3 and 5 which is 15.  On the 15th day after today, she will do both on the same day.

Answer 2

we know that

The least
common multiple (LCM) of two or more numbers is the least

number, other than zero, that is a multiple of all the numbers.

In this problem, we are looking for the least common multiple of $3$ and $5$

So

Multiply $3$ by $5$

$LCM=3*5\\ LCM=15$

therefore

On the $15th$ day after today, she will do both on the same day

the answer is

$15 days$