12=-0.01x^2+0.7x+6

Solution for 12=-0.01x^2+0.7x+6 equation:

12=-0.01x^2+0.7x+6

We move all terms to the left:

12-(-0.01x^2+0.7x+6)=0

We get rid of parentheses

0.01x^2-0.7x-6+12=0

We add all the numbers together, and all the variables

0.01x^2-0.7x+6=0

a = 0.01; b = -0.7; c = +6;
Δ = b2-4ac
Δ = -0.72-4·0.01·6
Δ = 0.25
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{-(-0.7)-\sqrt{0.25}}{2*0.01}=\frac{0.7-\sqrt{0.25}}{0.02}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-0.7)+\sqrt{0.25}}{2*0.01}=\frac{0.7+\sqrt{0.25}}{0.02}
$