- We have first find out the factors of the numbers.
- Factors of 15 are 1, 3, 5, 15.
- Factors of 20 are 1, 2, 4, 5, 10, 20.
- Factors of 21 are 1, 3, 7, 21.
- Factors of 34 are 1, 2, 17, 34.
- Therefore, there are no numbers in the list, which are divisible by 5, 10 and 15.
- 15 can be divisible by 5 and 15 not 10.
- 20 can be divisible by 5 and 10 not 15.
Hope you could get an idea from here.
Doubt clarification - use comment section.