x+x(12/100)=12

Solution for x+x(12/100)=12 equation:

x+x(12/100)=12

We move all terms to the left:

x+x(12/100)-(12)=0

We add all the numbers together, and all the variables

x+x(+12/100)-12=0

We multiply parentheses

12x^2+x-12=0

a = 12; b = 1; c = -12;
Δ = b2-4ac
Δ = 12-4·12·(-12)
Δ = 577
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)-\sqrt{577}}{2*12}=\frac{-1-\sqrt{577}}{24}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+\sqrt{577}}{2*12}=\frac{-1+\sqrt{577}}{24}
$