CPM Homework Help : CCA Problem 4-12

For each of the following generic rectangles, find the dimensions (length and width) and write the area as the product of the dimensions and as a sum.

Generic rectangle
left interior $3y^2$
interior right $-12y$
Hint (a):
Find the length and width of each small rectangle.
Answer (a):
Generic rectangle
top edge left $y$
top edge right $-4$
left edge $3y$
interior left $3y^2$
interior right $-12y$
$3y(y−4)=3y^2−12y$

Generic rectangle interior top left $3y^2$
interior top right $-12y$
interior bottom left $5y$
interior bottom right $-20$

Hint (b):
Follow the steps in part (a).
Answer (b):
Generic rectangle
top edge left $y$
top edge right $-4$
left edge top $3y$
interior left top $3y^2$
interior right top $-12y$
left edge bottom $5$
interior left bottom $5y$
interior right bottom $-20$
$(3y+5)(y−4)=3y^2−7y−20$