Answer:
-66 m/s
Explanation:
In physics, when you are dealing with parabolic movement or parabolic launch, you have to keep in mind that you will always have the gravity as your de-acceleration, so in this case acceleration rate is 9.81 m/s2 and as the cannonball and the target were at the same height, this means that the parabole was complete and that it had already covered the same distance going up as going down, so it will hit the target at the same Y-velocity only negative since it is falling.