In getting the x, you must first convert the said data in to a slope intercept form and the formula for it is y = mx+b so the slope is 7/16 while the y is 3.5. In that data its self you can came up with the equation of 3.5 = 7/16x + 0 and the value of X would be 8. I hope you are satisfied with my answer
D. is the answer
y - y1 = m(x - x1)
the slope is 2/3, so choose which point to be (x1, y1)
Look at the graph at which x=3, then look and see what value y is and that will give you f(3).
11.70 gallons....................................