5n^2=280-5n

Solution for 5n^2=280-5n equation:

5n^2=280-5n

We move all terms to the left:

5n^2-(280-5n)=0

We add all the numbers together, and all the variables

5n^2-(-5n+280)=0

We get rid of parentheses

5n^2+5n-280=0

a = 5; b = 5; c = -280;
Δ = b2-4ac
Δ = 52-4·5·(-280)
Δ = 5625
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{5625}=75$
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(5)-75}{2*5}=\frac{-80}{10}
=-8
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(5)+75}{2*5}=\frac{70}{10}
=7
$