0=-30.6+24.5x-4.9X^2

Solution for 0=-30.6+24.5x-4.9X^2 equation:

0=-30.6+24.5x-4.9x^2

We move all terms to the left:

0-(-30.6+24.5x-4.9x^2)=0

We add all the numbers together, and all the variables

-(-30.6+24.5x-4.9x^2)=0

We get rid of parentheses

4.9x^2-24.5x+30.6=0

a = 4.9; b = -24.5; c = +30.6;
Δ = b2-4ac
Δ = -24.52-4·4.9·30.6
Δ = 0.4899999999999
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-24.5)-\sqrt{0.4899999999999}}{2*4.9}=\frac{24.5-\sqrt{0.4899999999999}}{9.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-24.5)+\sqrt{0.4899999999999}}{2*4.9}=\frac{24.5+\sqrt{0.4899999999999}}{9.8}
$