Answer :
For the information given in the statement let:
*h: number of hours the bike was rented
*R(h): total cost of renting the bike
So you have the following linear equation
[tex]R(h)=8h+18[/tex]And since Melanie paid $74 to rent a bike then
[tex]\begin{gathered} R(h)=74 \\ \text{ Replacing} \\ 74=8h+18 \end{gathered}[/tex]Now you can solve for h
[tex]\begin{gathered} 74=8h+18 \\ \text{ Subtract 18 from both sides of the equation} \\ 74-18=8h+18-18 \\ 56=8h \\ \text{ Divide by 8 into both sides of the equation} \\ \frac{56}{8}=\frac{8h}{8} \\ 7=h \end{gathered}[/tex]Therefore, Melanie paid for a 7 hours bike rental.