Answer:
-3mn
Step-by-step explanation:
It seems you might be missing some of the question, as you haven't given what m and n are equal to.
If the question has just given you x, then you would simply just simplify it to get -3mn.
First thing First. You must find have a common denominator. If you want to find it then you do this
3: 3 6 9 12 15 18 21
7: 7 14 21 28
Once you found a number they have in common (21) You do this next
3/7 * 3/3 = 9/21
2/3 * 7/7 = 14/21
Now the next thing you do is subtract your numerators but not the denominators
14-9=5
5/12
you cant simplified so your done! Hope this helps!!!! <span />
C is the closet to the real answer and its a estimate so, C
-4/10+5/10
=5/10-4/10
=1/10
L*w=area
(3x+21)*w=3x^2+33x+84
w=(3x^2+33x+84)/3x+21
(3(x+4)(x+7))/3(x+7)
w=x+4
