How do i find the velocity and how long will it take for the ball to reach it's maximum height?

So hmm check the picture below





part 1)  

it takes  

part 2)



it will reach the maximum height at   

how much higher than before is that? well, what was the y-coordinate for when the vₒ was 64? what did you get for  ?

subtract that from this height when vₒ is 128 or doubled, to get their difference, that's how much higher it became