157=157-9t-16t^2

Solution for 157=157-9t-16t^2 equation:

157=157-9t-16t^2

We move all terms to the left:

157-(157-9t-16t^2)=0

We get rid of parentheses

16t^2+9t-157+157=0

We add all the numbers together, and all the variables

16t^2+9t=0

a = 16; b = 9; c = 0;
Δ = b2-4ac
Δ = 92-4·16·0
Δ = 81
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{81}=9$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(9)-9}{2*16}=\frac{-18}{32}
=-9/16
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(9)+9}{2*16}=\frac{0}{32}
=0
$