The ratio of the time of flight for the two balls will be equal to 1.
This is a great example of a trick question.
When you launch an object horizontally from a height
The launch velocities have no impact on the total time of flight, they only affect the horizontal distance covered by the object.
The movement of the two balls has a horizontal component and a vertical component. The same can be said for the initial velocity.
When you launch a ball horizontally, the angle it makes with the horizontal is equal to
Since the initial velocity has no vertical component, the vertical displacement will be equal to
This means that you have