-3c=-7c^2

Solution for -3c=-7c^2 equation:

-3c=-7c^2

We move all terms to the left:

-3c-(-7c^2)=0

We get rid of parentheses

7c^2-3c=0

a = 7; b = -3; c = 0;
Δ = b2-4ac
Δ = -32-4·7·0
Δ = 9
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{9}=3$
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-3)-3}{2*7}=\frac{0}{14}
=0
$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-3)+3}{2*7}=\frac{6}{14}
=3/7
$