C)
Area of full triangle
1/2(8)(6)=24cm^2
Area of non shaded triangle
1/2(4)(3)=6cm^2
Area of full minus area of small triangle
24-6=18cm^2
D)
Area of Big rectangle
(4)(12)=48
Area of non shaded triangle
1/2(9)(4)=18
Area of Big rectangle minus non shaded triangle
48-18=30cm^2