20=0.07x^2-1.1x+24

Solution for 20=0.07x^2-1.1x+24 equation:

20=0.07x^2-1.1x+24

We move all terms to the left:

20-(0.07x^2-1.1x+24)=0

We get rid of parentheses

-0.07x^2+1.1x-24+20=0

We add all the numbers together, and all the variables

-0.07x^2+1.1x-4=0

a = -0.07; b = 1.1; c = -4;
Δ = b2-4ac
Δ = 1.12-4·(-0.07)·(-4)
Δ = 0.09
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{-(1.1)-\sqrt{0.09}}{2*-0.07}=\frac{-1.1-\sqrt{0.09}}{-0.14}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1.1)+\sqrt{0.09}}{2*-0.07}=\frac{-1.1+\sqrt{0.09}}{-0.14}
$