The equation used to solve this problem is this:
H(t) = -16t^2 +vt + s
Where,
H(t) is the distance of the ball from the ground in feet,
t is the time in seconds,
v is the initial velocity of the ball as it is thrown up in feet/sec,
s is the distance of the ball from the ground when it was thrown in feet
Plugging in the given values,
0 = 16 t^2 + 35t + 0
This is a quadratic equation and the roots are:
0 and 2.19
answer: 2.19 seconds