To find out how many gallons of gasoline Trisha can purchase with $30, we look at the point \( X \) on the graph, which is at \( (9.375, 30) \).
The x-coordinate \( 9.375 \) represents the number of gallons, and the y-coordinate \( 30 \) represents the cost in dollars.
Since the question asks to state the number of gallons of gasoline she can purchase to the nearest whole number, we round \( 9.375 \) to the nearest whole number, which is \( 9 \).
Thus, Trisha can purchase 9 gallons of gasoline.