On every 3rd day ivan goes to the gym to exercise. every 5th day gavin goes to the gym to exercise. what is the first day ivan and gavin will go to the gym at the same time?

The first day Ivan and Gavin will go to the gym at the same time is on the 15th day.

Explanation:
To solve this, we have to find the LCM (least common multiple) of 3 and 5, because we want the numbers to land together. To do this, let's list the first couple multiples of 3 and 5

3: 3,6,9,12,15,18,21
5: 5,10,15,20,25,30

As you can see, 15 is the first common multiple we see on the list.

Ivan and Gavin will go to the gym together day 15 because the least common multiple of 3 and 5 is 15