-2(-6-7n)5n=145

Solution for -2(-6-7n)5n=145 equation:

-2(-6-7n)5n=145

We move all terms to the left:

-2(-6-7n)5n-(145)=0

We add all the numbers together, and all the variables

-2(-7n-6)5n-145=0

We multiply parentheses

70n^2+60n-145=0

a = 70; b = 60; c = -145;
Δ = b2-4ac
Δ = 602-4·70·(-145)
Δ = 44200
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{44200}=\sqrt{100*442}=\sqrt{100}*\sqrt{442}=10\sqrt{442}$
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(60)-10\sqrt{442}}{2*70}=\frac{-60-10\sqrt{442}}{140}
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(60)+10\sqrt{442}}{2*70}=\frac{-60+10\sqrt{442}}{140}
$