25c^2-5c-16=-4

Solution for 25c^2-5c-16=-4 equation:

25c^2-5c-16=-4

We move all terms to the left:

25c^2-5c-16-(-4)=0

We add all the numbers together, and all the variables

25c^2-5c-12=0

a = 25; b = -5; c = -12;
Δ = b2-4ac
Δ = -52-4·25·(-12)
Δ = 1225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1225}=35$
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-5)-35}{2*25}=\frac{-30}{50}
=-3/5
$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-5)+35}{2*25}=\frac{40}{50}
=4/5
$