Newton High School is selling bag lunches for a field trip.  The price of $3$ lunches is given to be $\$4.50$. Tyler wants to know if he can afford to buy himself and $4$ of his friends lunch.  If the price of each lunch is fixed, how much money does Tyler need?
Since $3$ lunches sell for $\$4.50$, each lunch sells for $\frac{\$4.50}{3}=\$1.50$.  Thus the total cost of $5$ lunches is $5 \times \$1.50=\boxed{\$7.50}$.