Work out the percentage of the area inside the square that is shaded.

55%.

Step-by-step explanation:

Since we know that all sides of a square have equal length and perimeter of a square is 4 times the length of one side of square, so we can find length of each side of square by multiplying 40 by 4.  

Now we will find the area of our square with side length 10.

Now we will find the area of shaded region by subtracting the non-shaded area of square from the total area of square. We can see that non-shaded part of our square is in form of two right triangle.

Let us find area of triangle whose base is 10 cm and height is 6 cm (10-4).

Now let us find area of triangle whose base is 10 cm (vertical)  and height is 3 cm (10-7).

Now let us find area of shaded part inside square by subtracting area of two triangles from area of square.

Therefore, area of shaded part inside square is

Now let us find 55 is what percent of 100.

Therefore, 55% of the area inside the square is shaded.                      

step-by-step explanation: