Answer:
I am not in your grade that Is way to hard
In mathematics, 'is' would be the equal sign. And 'of' would be the multiplcation sign. The missing number would be any variable.
56 is 28% of a number would be translated algebraically to:

Solving for x, we get:

Divide 28 on both sides

Multiply 100 on both sides
56 is 28% of 200
See attached picture for answer:
You would need to know the length of two sides either a2, b2, c2. you would also need to know what sides you are solving for, either one of the legs or hypotenuse. hope this helps, if you know how to solve a Pythagorean theorem problem this should be easy to answer