Given the information, we have the following:
Therefore, we have the following relationship:
[tex]\begin{gathered} A=b\cdot h \\ \Rightarrow294=x\cdot(x+7) \\ \Rightarrow x^2+7x-294=0 \end{gathered}[/tex]Now, solving for x we get the following values:
[tex]\begin{gathered} x^2+7x-294=0 \\ \Rightarrow(x+21)\cdot(x-14)=0 \\ x=-21 \\ or \\ x=14 \end{gathered}[/tex]Since we cannot have a negative length, we take x=14, therefore:
Finally, the longer side of the room is 21 ft