In order to calculate the value of each missing variable, we need to know that the area of a square is given by the length of its side squared.
So, for the yellow triangle, we have:

For the blue square:

Now, we can use the Pythagorean Theorem to find the value of b:

Now, for the area of the red square:

Doing the same for the other figure, we have:

The area of a right triangle is half the product of the legs, so let's calculate the missing leg (that is, the value of c) using the Pythagorean Theorem:
