SOLUTION
Given the question, the following are the solution steps to answer the question.
STEP 1: Decide the formula to use
Since it can be seen from the question that order is important, we use the Permutation approach which is given by the formula:
[tex]^nP_r=\frac{n!}{\left(n-r\right)!}[/tex]STEP 2: Find the number of possible ways
[tex]\begin{gathered} n=7,r=1\left(opening\right)+1\left(middle\right)+1\left(ending\right)=3 \\ we\text{ have;} \\ ^7P_3=\frac{7!}{\left(7-3\right)!}=\frac{7!}{4!}=\frac{7\times6\times5\times4!}{4!}=7\times6\times5=210 \end{gathered}[/tex]Hence, there are 210 possible ways
