So with this, you will be using proportions. In this case, our proportion is: 
Firstly, cross-multiply: x^2=144
Next, square root both sides of the equation, and your answer will be x = 12
Sorry, it's a test question. Not actually allowed to help...
Answer:
60
Step-by-step explanation:
All angles = 180
All sides are equal
Therefore, 180/3 = angle degrees = 60
x is an opposite angle of bottom right angle therfore x = 60
Answer:
31/8
Step-by-step explanation: