A tank holds 3,000 gallons of water, which drains from the bottom of the tank in half an hour. The values in the table show the volume V of water remaining in the tank (in gallons) after t minutes. (a) (b) t (min) 5 10 15 20 25 30 V (gal) 2,076 1,314 795 345 84 0 If P is the point (15,795) on the graph of V, find the slopes of the secant lines PQ when Q is the point on the graph with t 5, 10, 20, 25, and 30. (Round your answers to one decimal place.) Q (5, 2,076) (10, 1,314) (20, 345) (25,84) (30,0) Slope Estimate the slope of the tangent line at P by averaging the slopes of the two adjacent secant lines corresponding to the two points closest to