To factor the expression 6m - 21p, we can look for the greatest common factor (GCF) of the two terms. In this case, the GCF is 3, because it is the largest number that evenly divides both 6 and 21.
So we can begin by factoring out the GCF of 3:
3(2m - 7p)
Therefore, 6m - 21p can be factored as 3(2m - 7p).
