(3b+3)(5b+8)=0

Solution for (3b+3)(5b+8)=0 equation:

(3b+3)(5b+8)=0

We multiply parentheses ..

(+15b^2+24b+15b+24)=0

We get rid of parentheses

15b^2+24b+15b+24=0

We add all the numbers together, and all the variables

15b^2+39b+24=0

a = 15; b = 39; c = +24;
Δ = b2-4ac
Δ = 392-4·15·24
Δ = 81
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{81}=9$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(39)-9}{2*15}=\frac{-48}{30}
=-1+3/5
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(39)+9}{2*15}=\frac{-30}{30}
=-1
$