To help Mary Lou figure out the cost to fill up the car's gas tank, we need to use the unit rate of [tex]$3.50 per gallon and apply it to different quantities (3, 5, and 7 gallons) as given in the table.
1. For 3 gallons:
To find the cost for 3 gallons, we multiply the unit price ($[/tex]3.50 per gallon) by the number of gallons (3).
[tex]\[
a = 3 \text{ gallons} \times \$3.50/\text{gallon} = \$10.50
\][/tex]
2. For 5 gallons:
To find the cost for 5 gallons, we multiply the unit price ([tex]$3.50 per gallon) by the number of gallons (5).
\[
b = 5 \text{ gallons} \times \$[/tex]3.50/\text{gallon} = \[tex]$17.50
\]
3. For 7 gallons:
To find the cost for 7 gallons, we multiply the unit price ($[/tex]3.50 per gallon) by the number of gallons (7).
[tex]\[
c = 7 \text{ gallons} \times \$3.50/\text{gallon} = \$24.50
\][/tex]
Putting these values in the table, we get:
\begin{tabular}{|c|c|}
\hline Price & Gallons Purchased \\
\hline[tex]$\$[/tex] 3.50[tex]$ & 1 \\
\hline$[/tex]\[tex]$ 10.50$[/tex] & 3 \\
\hline[tex]$\$[/tex] 17.50[tex]$ & 5 \\
\hline$[/tex]\[tex]$ 24.50$[/tex] & 7 \\
\hline
\end{tabular}
In conclusion:
[tex]\[
\begin{array}{l}
a = \$10.50 \checkmark \\
b = \$17.50 \checkmark \\
c = \$24.50 \checkmark
\end{array}
\][/tex]
