For this case we have:
Question 1:

By definition, one of the properties of the rectangle states that:
The opposite sides of a rectangle have the same length, that is, they are equal, then:

So:

Clearing "y" we have:

Thus, the value of "y" is 5.
Answer:

Question 2:

By definition, one of the properties of the rectangles states that:
The diagonals of a rectangle have the same lengths, that is:

We clear the value of "x":

We must find DB:

ANswer:

Question 3:

By definition, one of the properties of the rectangles states that:
The diagonals of a rectangle intersect and at the point of intersection they are divided in half, that is:

Clearing the value of "x" we have:

We know that:

ANswer:

Question 4:

By definition, one of the properties of the rectangles states that:
The 4 angles of the rectangles are straight. From there it turns out that:

We clear the value of "x":

So:

Answer:
