Question 806965
The vertex is
 (25/16, 721/16)=(1.5625, 45.0625)
your 25/16 is correct. It is the exact answer.
-16t^2 + 50t + 6 
-16(25/16)^2 + 50(25/16) +6 
 You have
-16(25/16)^2 + 50(25/16) - 16
where did you get the final -16
that changes the height by 22