0=15n-3n^2

Solution for 0=15n-3n^2 equation:

0=15n-3n^2

We move all terms to the left:

0-(15n-3n^2)=0

We add all the numbers together, and all the variables

-(15n-3n^2)=0

We get rid of parentheses

3n^2-15n=0

a = 3; b = -15; c = 0;
Δ = b2-4ac
Δ = -152-4·3·0
Δ = 225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{225}=15$
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-15)-15}{2*3}=\frac{0}{6}
=0
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-15)+15}{2*3}=\frac{30}{6}
=5
$