Im all most postive it is b 471cm but im not sure i hope this helps
First find the area of the rectangle by multiplying the length and width of the rectangle, so 12 x25=300. Then find the area of the triangle, which is length x height/ 2. So 8 x 25=200/2=100. Then add the two answers together to get 400.
So WX is 7y +4 and XY is 21, and when you add those lines you get the whole thing, which is 12y so write that like an equation
12y = 7y+4+21
12y = 7y+25
5y = 25
y = 5