Ineed to find the area of the shaded region but i need detailed steps to do it

First, you need to find the total area of the rectangle:
20x25=500
Next, you have to find the are of the two halve circles (since there are two halves you only have two find the area of one circle.)
A=πr²
you have to find r (radius) 
first find the diameter
4.5(2)=9
25-9=16
find the radius:
16/2=8
r=8
Now fill in the information you have:
A=π8²
solve:
A=π64
A≈201.06
Next, you have to subtract the area of the circle from the area of the rectangle in order for you to find the area of the (rather weird) shape:
500-201.06= 298.94.
The answer is 298.94cm
I'm sorry it took me so long...
Hope I helped...
It should be right.