-7y-4=y*(8-6)-64

Solution for -7y-4=y*(8-6)-64 equation:

-7y-4=y(8-6)-64

We move all terms to the left:

-7y-4-(y(8-6)-64)=0

We add all the numbers together, and all the variables

-7y-(y2-64)-4=0

We get rid of parentheses

-7y-y2+64-4=0

We add all the numbers together, and all the variables

-1y^2-7y+60=0

a = -1; b = -7; c = +60;
Δ = b2-4ac
Δ = -72-4·(-1)·60
Δ = 289
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{289}=17$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-7)-17}{2*-1}=\frac{-10}{-2}
=+5
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-7)+17}{2*-1}=\frac{24}{-2}
=-12
$