To factor this polynomial you will have to first find the GCF of 81 and 48 and its 3.
So then you put 3 out the parentheses. 3(----).
Then you have to see how many times 3 goes into 81m and 48m. It is 27m and 16mn.
So then this is what you get, 3(27m-16mn)
Hope it helps you!!!