x*(10/100)=120

Solution for x*(10/100)=120 equation:

x(10/100)=120

We move all terms to the left:

x(10/100)-(120)=0

We add all the numbers together, and all the variables

x(+10/100)-120=0

We multiply parentheses

10x^2-120=0

a = 10; b = 0; c = -120;
Δ = b2-4ac
Δ = 02-4·10·(-120)
Δ = 4800
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{4800}=\sqrt{1600*3}=\sqrt{1600}*\sqrt{3}=40\sqrt{3}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-40\sqrt{3}}{2*10}=\frac{0-40\sqrt{3}}{20}
=-\frac{40\sqrt{3}}{20}
=-2\sqrt{3}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+40\sqrt{3}}{2*10}=\frac{0+40\sqrt{3}}{20}
=\frac{40\sqrt{3}}{20}
=2\sqrt{3}
$