(2x+30)(7x-3)=90

Solution for (2x+30)(7x-3)=90 equation:

(2x+30)(7x-3)=90

We move all terms to the left:

(2x+30)(7x-3)-(90)=0

We multiply parentheses ..

(+14x^2-6x+210x-90)-90=0

We get rid of parentheses

14x^2-6x+210x-90-90=0

We add all the numbers together, and all the variables

14x^2+204x-180=0

a = 14; b = 204; c = -180;
Δ = b2-4ac
Δ = 2042-4·14·(-180)
Δ = 51696
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:

$\sqrt{\Delta}=\sqrt{51696}=\sqrt{144*359}=\sqrt{144}*\sqrt{359}=12\sqrt{359}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(204)-12\sqrt{359}}{2*14}=\frac{-204-12\sqrt{359}}{28}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(204)+12\sqrt{359}}{2*14}=\frac{-204+12\sqrt{359}}{28}
$