Question 95463
Let h=0 because the height is zero when the object hits the ground.
Then solve for t.
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h = –16t^2 + 30t + 4. 
-16t^2+30t+4 = 0
Divide thru by -2 to get:
8t^2-15t-2 = 0
Factor to get:
(8t+1)(t-2)= 0
Positive solution:
t = 2 seconds

Cheers,
Stan H.