To determine how many gallons of gasoline Trisha can purchase with $30, we refer to the point \( X (9.375, 30) \) on the graph. This point indicates that when the cost is $30, Trisha can buy approximately 9.375 gallons of gasoline.
Since we are asked to state the number of gallons to the nearest whole number, we round 9.375 to the nearest whole number, which is 9.
Thus, Trisha can purchase approximately 9 gallons of gasoline.