In this case we have to divide the length of the wall by the width of a cabinet. Doing so, we have:
[tex]\begin{gathered} 2\frac{1}{2}=\frac{2\cdot2+1}{2}=\frac{5}{2}\text{ (Converting the mixed number to an improper fraction)} \\ \frac{15}{1}\div\frac{5}{2}=\frac{15\cdot2}{5}(\text{Dividing fractions)} \\ \frac{15\cdot2}{5}=\frac{30}{5}=6\text{ (Simplifying the result)} \\ \text{The answer is 6 cabinets.} \end{gathered}[/tex]