Question 333292
If you were given 3m-6n-15 and want to find the original expression, just factor out a common term and then divide it by every term found in the expression 3m-6n-15.

The common factor is 3.

3m/3 = m

-6n/3 = -2n

-15/3 = -5

You started with 3(m - 2n - 5).