-2(y-3)7y=30

Solution for -2(y-3)7y=30 equation:

-2(y-3)7y=30

We move all terms to the left:

-2(y-3)7y-(30)=0

We multiply parentheses

-14y^2+42y-30=0

a = -14; b = 42; c = -30;
Δ = b2-4ac
Δ = 422-4·(-14)·(-30)
Δ = 84
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{84}=\sqrt{4*21}=\sqrt{4}*\sqrt{21}=2\sqrt{21}$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(42)-2\sqrt{21}}{2*-14}=\frac{-42-2\sqrt{21}}{-28}
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(42)+2\sqrt{21}}{2*-14}=\frac{-42+2\sqrt{21}}{-28}
$