Answer
See below
Work Step by Step
Substitute $n=8,r=3$ into the formula $_n C_r=\frac{n!}{(n-r)!.r!}$ to find how many different smoothies you can make if you choose three fruits from a list of eight of them:
$$_8 C_3=\frac{8!}{(8-3)!3!}=\frac{8!}{5!3!}=56$$
