3,419,000 because the 913 rounds the number up
Simple...
you have:

You want to find m-->>>
1.)Isolate m

Leaving you with...
F*

=

Keep isolating m-->>>


Square root to solve what just m is-->>>

=

That is how you solve for m...
Thus, your answer.
The best way to do this is to make up values for the sides.
Say the lengths of square B's sides are each 4 cm. That means A's sides are 2 cm.
So, the area of square B is 4^2 = 16 cm^2, and A's area is 4 cm^2. We can see the shaded area is half of A, so it's 2 cm^2.
What percent of 16 is 2?
2 / 16 * 100 = 12.5%