The answer to this is
3(x+1)(x+8)
Both angles 2x+6 and 96 shown are vertically opposite angles and vertically opposite angles are always equal
so 2x+6 should be equal to 96
so 2x + 6 = 96
Now we have to solve for x here and have to get x by itself on left hand side
So first get rid of +6 by doing its opposite -6 on both sides
2x + 6 -6 = 96 -6
2x = 90
Now to get x by itself we have to get rid of 2, for that divide both sides by 2

x = 45
Hence proved that x = 45
Add (-2X) to both sides:
2X + B + (-2X) = C + (-2X)
If we (rearrange) it into B + 2X + (-2X) = C + (-2X)
B + 2X - 2X = C + (-2X)
Since +2X - 2X = 0
B + 0 = C + (-2X)
B = C + (-2X)
B = C - 2X