Math homework

The factors of 3 are 3 and 1, so the only possible common factors among all of the given numbers are 1 and 3. One is a factor of 3, 6, 5, and 10 so it's a common factor. But 3 is not a factor 5 so it's not common to all four numbers (there is no integer that when multiplied by 3 will give 5). So the only common factor is 1.