Three rectangles are in a row, as shown below.
The first and second rectangles have a combined width equal to 7 m.
The second and third have a combined width equal to 8 m.
If the first rectangle has an area equal to 20 m2 and the third has an area equal to 25 m2, what is the area of the second rectangle?

In rectangle ABCD, a semicircle CPS is drawn as shown below.
The semicircle’s diameter is shared with and extends beyond side BC, it intersects side AB at Q, and it is tangent to side AD at S.
If CQ = 10, what is the area of rectangle ABCD?

A rectangle is divided by four lines, as shown, with 4 of the resulting triangles having known areas. Find the area of the quadrilateral that is shaded in grey.