So, when doing this kind of problems, the first thing that we would want to do is to add up (all) the numbers first, and by doing this, it would look like the following:

Then, we would then divide it by how many numbers they are.

Your answer:
7
Because this is a triangle and we know that we can use the Pythagorean Theorem to find the hypotenuse we just plug in the numbers. But because you have the hypotenuse already you will subtract the leg from the hypotenuse.
A^2+B^2=C^
16^2+B^2=20^2
256+B^2=400 subtract 256 from both sides
B^2=144 now take the square root of both sides
B=12
The second leg is 12 cm long. Your answer is B, the second answer.
Answer:
x=0,3
Step-by-step explanation:
start by dividing every term by 3
x^3-3x^2+x-3
group into 2 terms
(x^3-3x^2)+(x-3)
simplify as much as you can
x^2(x-3)+(x-3)
combine terms
(x^2)(x-3)
x=3, 0
Using complementary angles, <X is equal to <Z, so it's <Z = 35°.