X+x(20/100)=250

Solution for X+x(20/100)=250 equation:

X+X(20/100)=250

We move all terms to the left:

X+X(20/100)-(250)=0

We add all the numbers together, and all the variables

X+X(+20/100)-250=0

We multiply parentheses

20X^2+X-250=0

a = 20; b = 1; c = -250;
Δ = b2-4ac
Δ = 12-4·20·(-250)
Δ = 20001
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{20001}}{2*20}=\frac{-1-\sqrt{20001}}{40}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+\sqrt{20001}}{2*20}=\frac{-1+\sqrt{20001}}{40}
$