The two squares and the shaded region of square A is in the attachment.
Answer: The shaded region of A is 12.5% of the area of B.
Step-by-step explanation: Assume that the length of side of square A is a and the length of side of square B is b.
Length a is half (50%) of length b:
a =

The shaded region is a triangle. The area of a triangle is: A =

b and h are the sides of the square A, so:
=



Area of square B is:
= b.b

Comparing areas:
=
=

As percentage:
× 100 = 0.125 × 100 = 12.5%
Comparing the shaded region of A to square B, the area of the first is 12.5% smaller than the second.