Answer :
We have the following situation:
1/12B ---> 15 min = 1/4h
Then, at this rate, we have that the cookies that she is going to sell are:
[tex]\frac{1}{12}B\Rightarrow\frac{1}{4}h\Rightarrow4\cdot(\frac{1}{12}B)\Rightarrow4\cdot(\frac{1}{4}h)\Rightarrow\frac{1}{3}B\Rightarrow1h[/tex]Then, at this rate, they are going to sell 1/3 of the boxes in one hour.
With the way of posing the question above, we can have the same result:
[tex]x\cdot\frac{1}{4}h=1h\cdot\frac{1}{12}B\Rightarrow x=(1h\cdot\frac{1}{12}B)/(\frac{1}{4}h)\Rightarrow x=\frac{4}{12}B\Rightarrow x=\frac{1}{3}B[/tex]At this rate, they could sell 1/3 boxes in one hour.
