a cannon-ball is fired horizontally from the top of a castle wall with the speed of 80m/s. At the same time a cannon-ball is dropped straight down…

a cannon-ball is fired horizontally from the top of a castle wall with the speed of 80m/s. At the same time a cannon-ball is dropped straight down and strikes the ground in 2 seconds. How far from the castle wall does the first cannon-ball land?