Algebra
posted by Amy .
solve step by step
0=2(8t^232t+21)

16t^2 + 64t  42 = 0
Divide end values into two factors (7,6 or 7,6, or 21,2 or 21,2 or 14, 3 or so on) (16,1 or 16,1 or 4,4 or 8, 2 and so on) to see how their sum will get the center value.
From there it is trial and error. Start trying.