.05x.07(100-x)=6.6

Solution for .05x.07(100-x)=6.6 equation:

.05x.07(100-x)=6.6

We move all terms to the left:

.05x.07(100-x)-(6.6)=0

We add all the numbers together, and all the variables

.05x.07(-1x+100)-(6.6)=0

We add all the numbers together, and all the variables

.05x.07(-1x+100)-6.6=0

We multiply parentheses

-1x^2+100x-6.6=0

a = -1; b = 100; c = -6.6;
Δ = b2-4ac
Δ = 1002-4·(-1)·(-6.6)
Δ = 9973.6
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{-(100)-\sqrt{9973.6}}{2*-1}=\frac{-100-\sqrt{9973.6}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(100)+\sqrt{9973.6}}{2*-1}=\frac{-100+\sqrt{9973.6}}{-2}
$