Just think of the two parts cut out as quarter circles. You have a point thats the center of the circle and a point thats at the edge. Using the distance formula for points you can calculate the length that line. Thats the radius of the circle, area of the circle is 2piradius, then you have to divide that by 4 to get the area of the missing part.

Same with the bottom left. You calculate those two quarter circle areas and subtract it from the length times width of the entire rectangle.

Ohhh looking closer at the image they actually give you the corresponding radius length of each circle "R10, and R5" so its actually a little easier. No distance formula needed.