There's nothing wrong with your set up, must be in the algebra.
I get 21/2.
Find the volume of the solid lying under the plane z=4x+3y+5 and above the rectangle R={(x,y) | -1<= x <= 0 , 2 <=y <=3}
which is wrong. The correct answer is
Can someone help me? I have a feeling I might have miss used -1,0 and 2,3 maybe.
I also have another question similar to this I will need help on because I'm not quite sure where to start.