其它
Lisa is buying potatoes at a grocery store. She can either spend $10$ dollars on a $25\text{-lb}$ bag or $15$ dollars on a $35\text{-lb}$ bag. Whic is the cheaper one? 
Overseas Competition->Knowledge Point->Word Problem Modules->Unitary Method Problems->Finding the Unit Rate and then the Total Value
$$\frac{10}{25}\textasciitilde\textbackslash$ \text{/lb}=0.4\textasciitilde\textbackslash$ \text{/lb}$$  $$\frac{15}{35}\textasciitilde\textbackslash$ \text{/lb}=0.43\textasciitilde\textbackslash$ \text{/lb}$$  $$\frac{10}{25}\textless\frac{15}{35}$$  So, the answer is $$A$$. 