25=2x^2-30x

Solution for 25=2x^2-30x equation:

25=2x^2-30x

We move all terms to the left:

25-(2x^2-30x)=0

We get rid of parentheses

-2x^2+30x+25=0

a = -2; b = 30; c = +25;
Δ = b2-4ac
Δ = 302-4·(-2)·25
Δ = 1100
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:

$\sqrt{\Delta}=\sqrt{1100}=\sqrt{100*11}=\sqrt{100}*\sqrt{11}=10\sqrt{11}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(30)-10\sqrt{11}}{2*-2}=\frac{-30-10\sqrt{11}}{-4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(30)+10\sqrt{11}}{2*-2}=\frac{-30+10\sqrt{11}}{-4}
$