6x^2+14x-12 is the answer
The small box is 384inches squared for the volume and the larger box is 2,700 inches squared so if you place the smaller box inside the larger box the room left inside the larger box would be 2,316 inches squared
Ok we need a common coefficient of either x or y:
12x+21y=3
12x+40y=60
We can subtract one from the other to get:
19y=57
Now divide by 19 to get:
y=3
Now if we sub this back in we see that:
3x+30=15
3x=-15
x=-5
4n - 6m = -2
Let n = -2
4(-2) - 6m = -2
-8 - 6m = -2
-6m = -2 +8
-6m = 6
m = 6/-6
m = -1
So, when n is -2, m is -1.
Now, do the same when n is -1 and again when n is 0.