It would be: 28*15 / 100 = 420 / 100 = 4.2
The area of the shaded region is 85 units cubed.
using the LCD method.... well, there are a couple of ways, but let's simply add them up.
well, the denominators are 5x and 2x... so the only LCD will just be 10x, since it's divisible by both, so let's use that one.

I believe the answer if there are 216 ways to do this, but I’m not entirely sure the question.
Discriminant = b^2 - 4ac, where a, b and c come from the form of the quadratic equation as ax^2 + bx + c
Discriminant = (4)^2 - 4(1)(5)
= 16 - 20
= -4
-4 < 0, therefor there are no roots
(If the discriminant = 0, then there is one root
If the discriminant > 0, there are two roots, and if it is a perfect square (eg. 4, 9, 16, etc.) then there are two rational roots
If the discriminant < 0, there are no roots)