Question

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 be at the gym on the same day.

Answer 1

you have to find the LCM (least common multiple) of both numbers.

3: 3, 6, 9, 12, 15
5: 5, 10, 15

ivan and gavin will be together at the gym on the 15th day.

Answer 2

the fifteenth day is the first day they'll cross paths because 15 is the lowest common multiple for 3 and 15 also 3x5=15