Ricardo and Kim rowed their canoes from their base camp to a fishing camp. They rowed a distance of x miles upstream on one river, (3x2 − 9) miles downstream on another river, and (2x + 9) miles acr

Ricardo and Kim rowed their canoes from their base camp to a fishing camp. They rowed a distance of x miles upstream on one river, (3x2 − 9) miles downstream on another river, and (2x + 9) miles across a calm lake. Which expression is equivalent to the total distance, in miles, Ricardo and Kim rowed their canoes?