Answer:
a.
![Volume=15^(3)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/gg9bkyoualkrllcg149ilutz90tw54mvb8.png)
b.
![volume=3375 in^(3)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/uwup7og7ax02hglqb877aewkvchluvhfo7.png)
Explanation:
a.
The volume of a cube of side length L is given by the formula;
![Volume=l^(3)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/tj5o5js3f8yq02qctx2xo7e64sfdld1mej.png)
Our side length is given as 15 inches. Thus;
![Volume=15^(3)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/gg9bkyoualkrllcg149ilutz90tw54mvb8.png)
b.
The power function obtained above can be simplified by the use of a calculator to obtain the volume of the cubic display case.
![volume=15^(3)=3375 in^(3)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/83nnqesqd4232yxj64ff6u98n2ogmiadlo.png)