Let’s assume that this is an “elastic collision of unequal masses” (see http://en.wikipedia.org/wiki/Elastic_collision, which will help you visualize this). Let’s also assume that the weight of the basketball is 1 pound and the weight of the bowling ball is 2 pounds, and that the basket ball is traveling from east to west at a speed (v) of 9 miles per hour, and the bowling ball is traveling west to east at 9 miles per hour.

After the collision the bowling ball reverse direction and travel at 3 miles per hour, and the basketball will reverse direction and travel at 15 miles per hour.