Answer:
Both balls reach the ground at the same time.
Step-by-step explanation:
You may ask why? Well, the first ball is thrown with a horizontal velocity, but the acceleration it has is the gravity, so it will have an accelerated motion on the Y axis, so if we drop a second ball at the same time it will have the same acceleration going down, so both balls reach the ground at the same instant, the first ball will have a horizontal displacement but it'll reach at the same time.