There are 3 holes because if you do 4 thats to high cuz you would get 12 hope this is what you mean
Answer:
D
Step-by-step explanation:
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