Number 8? I don't know which one you are talking about.
This is a question that can be solved with Pythagorean Theorem since it is a right triangle. The longest side, 29, is the hypotenuse and the sides 21 and x are the legs. So, the Pythagorean Theorem states,

Where,
c is the Hypotenuse, a and b are the legs. Putting the respective values gives us,

So, 20 is the side length of x.
ANSWER: 20
The answer would be twelve 12 because 6x.5 is 3 and 3+9 is equal to 12
Answer:
D
Step-by-step explanation: