0=-0.05x^2+8x-140

Solution for 0=-0.05x^2+8x-140 equation:

0=-0.05x^2+8x-140

We move all terms to the left:

0-(-0.05x^2+8x-140)=0

We add all the numbers together, and all the variables

-(-0.05x^2+8x-140)=0

We get rid of parentheses

0.05x^2-8x+140=0

a = 0.05; b = -8; c = +140;
Δ = b2-4ac
Δ = -82-4·0.05·140
Δ = 36
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{36}=6$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-8)-6}{2*0.05}=\frac{2}{0.1}
=20
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8)+6}{2*0.05}=\frac{14}{0.1}
=140
$