Let's start by converting the fractions to decimals. That would make it easier to work with.
1.25 = -4c + 0.25
Now let's solve.
1.25 = -4c + 0.25
1.25 - 0.25 = -4c + 0.25 - 0.25
1 = -4c
1/-4 = -4c/-4
-0.25 = c
You can convert this back to a fraction if you want.
-1/4 = c