15c^2=20c

Solution for 15c^2=20c equation:

15c^2=20c

We move all terms to the left:

15c^2-(20c)=0

a = 15; b = -20; c = 0;
Δ = b2-4ac
Δ = -202-4·15·0
Δ = 400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{400}=20$
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-20)-20}{2*15}=\frac{0}{30}
=0
$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-20)+20}{2*15}=\frac{40}{30}
=1+1/3
$