Answer:
The area of the shaded part is 100

Explanation:
Subtracting Areas:
We can find the shaded area by adding or subtracting areas.
We'll use the latter method.
The total shape is a rectangle of side lengths 15 cm and 10 cm. Thus its area is:

The area of each non-shaded square is:

The total non-shaded area is

Thus, the shaded area is:

The area of the shaded part is 100
