Pg 648 (580) - Q22
In order to find x, make the figure into a rectangle by drawing in
an imaginary corner. The dimensions of the triangle formed by x and
the imaginary lines would be 3, 4, and x because 10-6=4, and 6-3=3.
Recognize the Pythagorean triple making x equal to 5,
and then add up all the sides to obtain a perimeter of 30.