Which is the largest common factor of 30 and 45?

To determine the largest common factor of 30 and 45, we first find the factors of each number.

The factors of 30 are: 1, 2, 3, 5, 6, 10, 15, and 30.

The factors of 45 are: 1, 3, 5, 9, 15, and 45.

Next, we identify the common factors between the two sets. The common factors are: 1, 3, 5, and 15.

Among these common factors, the largest one is 15. Hence, 15 is the greatest number that divides both 30 and 45 without leaving a remainder.

The other options, while they are factors of 30 and 45, do not exceed 15 in terms of being the largest common factor. Thus, 15 stands out as the largest common factor of the two numbers.