-7(5+6b)4b=-4b+7

Solution for -7(5+6b)4b=-4b+7 equation:

-7(5+6b)4b=-4b+7

We move all terms to the left:

-7(5+6b)4b-(-4b+7)=0

We add all the numbers together, and all the variables

-7(6b+5)4b-(-4b+7)=0

We multiply parentheses

-168b^2-140b-(-4b+7)=0

We get rid of parentheses

-168b^2-140b+4b-7=0

We add all the numbers together, and all the variables

-168b^2-136b-7=0

a = -168; b = -136; c = -7;
Δ = b2-4ac
Δ = -1362-4·(-168)·(-7)
Δ = 13792
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{13792}=\sqrt{16*862}=\sqrt{16}*\sqrt{862}=4\sqrt{862}$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-136)-4\sqrt{862}}{2*-168}=\frac{136-4\sqrt{862}}{-336}
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-136)+4\sqrt{862}}{2*-168}=\frac{136+4\sqrt{862}}{-336}
$