Cleopatra was said to have withdrawn her fleet when he was supposed to help Mark Antony do battle against ..?

.....the Roman Naval Armada in the Nile river sometime in 31 B.C. (this is a very old problem). When her 35-meter barge retreated at a uniform speed of 30m/sec, it was pursued by a Roman "gunship" at 20m/sec uniform speed, directly following in a straight line behind. As her barge is still within range, the Roman cannon master ordered that their cannons, rated to have maximum range of 1 kilometer, be aimed to hit a spot 10 barge-lengths ahead of Cleopatra's barge, to anticipate the barge's forward motion. Given that the cannon is always consistent with its range capacity, using the usual amount of charge, calculate the angle at which the cannon should be elevated to hit that spot? If Cleopatra's barge was 500 meters away at the instant of firing, will it be hit?