25%=0.25
24*0.25=6
24-6=18
18 pairs are not black
<h3>
Answer: C) Discriminant</h3>
The formula for the discriminant is
d = b^2 - 4ac
If d < 0, then there are no real number solutions
If d = 0, then you have exactly one real solution
If d > 0, then you have two different real number solutions
I am not 100% positive but from what I remember learning I think the answer you are looking for on the first question is C.