When every third day and then goes to the gym to exercise on every fifth day Gavin go to the gym to exercise what is the first day Evan and Gavin will be at the gym on the same day

To get the answer is you have to get the numbers by 3 and 5 and see in what number they will have the same.

3 = 3, 6, 9, 12, 15, 18, 21, 24, 27,30

5 = 5, 10, 15, 20, 30

The first day they will go to the gym together would be 30.