Let's use the variable b to represent the white triangle base (which is the width of the rectangle), and the variable h to represent the white triangle height (which is the length of the rectangle).
The white triangle area is given by:
[tex]A=\frac{b\cdot h}{2}=22.5\text{ cm}^2[/tex]
The area of the rectangle is given by the product of its length and its width, so we have:
[tex]A_2=b\cdot h=2\cdot(\frac{b\cdot h}{2})=2\cdot A=2\cdot22.5=45\text{ cm}^2[/tex]
Therefore the correct option is C.
