First you create a proportion (30/100=x/120). After you solve this, next you subtract this answer from 120. Then create a proportion for 40% (40/100=x/120). Then add this number to the first answer you got when you subtracted the answer from your first proportion from 120.
Answer: OPTION C.
Step-by-step explanation:
1. To solve this problem you must apply the Pythagorean Theorem, which is shown below:

Where a is the hypotenuse, and b and c are the legs of the triangle.
2. When you solve for one of the legs and substitute values, you obtain that the result is:

Squaring a number means you're multiplying the number by itself. This would mean (6b)^2 = (6b)(6b).