Find area formula for shaded regions for both shapes

The area for 7 is the area of the rectangle- the area of the triangle.
A=15x10 - (1/2)x8x5
A=150 - 20
A=130
The area for 8 is the square - the half-circle
A= 4x4 - half-circle
A=16 - half-circle
Now a circle has an area of pi*r^2
Half that circle has an area of 1/2 pi r^2
The diameter of the circle is 4 so the radius is 2
A= 16 - (1/2)x Pi x(2)^2
A= 16 - 2pi
That's the "exact" answer, for an estimation plug 16 - 2*pi into the calculator