其它
Tom and Jerry found $\frac{1}{2}$ of a steak in the kitchen. Tom ate $\frac{1}{2}$ of the leftover steak and Jerry ate $\frac{1}{4}$ of it. They decided to give the rest to their friend Spike. What portion of the original steak would Spike get? 
Overseas Competition->Knowledge Point->Calculation Modules->Fractions
$\frac{1}{2}-\frac{1}{2}\times \frac{1}{2}-\frac{1}{2}\times \frac{1}{4}=\frac{1}{8}$ 