It will be around 15.8% if you get the blue marble
Basically, to solve this problem, you have to solve or every single multiple choice.
a)3-7+(-10)=3-7-10=-14
b)3+7-(-10)=3+7+10=20
c)3-7-(-10)=3-7+10=6
d)3+7+(-10)=3+7-10=0
Thus B is the right choice because B is the biggest
Since they are FEWER than 30 total cones, the sum of x small cones and y large one must be LESS THAN 30: x+y <30
He needs AT LEAST a dozen (12), so that means that 12 will work or more than 12: