I got this question wrong, so if someone can please help me with this, I would really appreciate it! Please and thank you!

15 in.

Step-by-step explanation:

The area of the left-most square is 81 in.^2. Area = L*W (Length times width), and since we know squares are always equal on each side, we can do 9*9=81. That means the left side of the triangle is 9.

Then, we move to the bottom-most square. The perimeter is 48 in. As said before, we know all sides of a square must be equal. We will divide 48 by 4, as that's how many sides a square has (mind-blowing!), and we get 12. That means, using the Pythagorean Theorem, (9^2) + (12^12) = C^2. We can simplify this to 81 + 144 = C^2, or 225 = C^2 if you add those two numbers together. We can take the square root of both sides to get C = 15!