Question

what is -(c-4)=5?so what is 'c'

Answer 1

-(c-4)=5
c-4=-5
c=-1

Check answer:
-(-1-4)=5
-(-5)=5
5=5

Answer 2

$-(c-4)=5 \\ \\ -c + 4 = 5 \\ \\ 4 - c = 5 \\ \\ -c = 5 - 4 \\ \\ -c = 1 \\ \\ c = -1$

The final result is: c = -1.