This is my math geometry... What does x equal on the shape to the right?

Answer:
x=12
Step-by-step explanation:
It is a textbook 3:4:5 triangle. The hypotenuse is 15 (5*3), and the base is 9 (3*3). Since they both share a common factor of 3, the 3rd side would be 4*3, which is 12.