First you make a graph with a line in the middle (horizontal)
and then put another line in the middle (Vertical). Then you
put x and +7 on the top (not in the graph out side of it, on
top) and put the x and 6 on the left side (not in the graph
but outside) then you work out x and x bit which would be
x2 then you will need to work out x and the 7 and what you
put for that is +7x. now you are going to work out the left
side, you already have the first box filled in which was x2,
now you will need to fill in the bottom left box which will be
x and +6 so you will need to put +6x for the bottom right you
do 6 x 7 which is -42 then work out 6-7 which is 13 and for
the answer you put x2 - 42x - 13
(This may be wrong but I understand It).
Volume
To work out volume you have
to work out the area of the
front side of the shape and
times it by how long it is