Please help with this 4 question

Which equation and solution can be used to solve this problem? thirteen less than a number is sixteen. 13-n=16: add 13 to both sides. the answer is 29. n+13=16: subtract 13 from both sides. the answer is 3. n+16=13 subtract 13 from both sides. the answer is 3. n-13=16: add 13 to both sides. the answer is 29.

Show your workcan a right triangle have this sides? *how to prove it without using the pythagorean theorema*

Which geometric principle is used to justify the construction below?