As Part of a Market Research Project, You Survey Six

As part of a market research project, you survey six random people to see how much gas per week they would buy at various prices. The data you collect is in the accompanying table. What is the total demand for gasoline at $2.50 per gallon in your survey?
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Quantity of Gallons of Gas Demanded Per Week
$$\begin{array} { | l | l | l | l | l | l | l | } \hline \text { Price per gallon of gasoline } & \text { Marty } & \text { Zain } & \text { Doc } & \text { Mikael } & \text { Zoya } & \text { Amirah } \\\hline \$ 1.50 & 10 & 15 & 6 & 20 & 20 & 6 \\\hline \$ 2.00 & 8 & 12 & 3 & 18 & 19 & 5 \\\hline \$ 2.50 & 6 & 9 & 1 & 14 & 17 & 4 \\\hline \$ 3.00 & 4 & 6 & 0 & 10 & 15 & 3 \\\hline \$ 3.50 & 2 & 3 & 0 & 4 & 12 & 1 \\\hline\end{array}$$

A) 51 gallons
B) 38 gallons
C) 77 gallons
D) 22 gallons