90-20.8=c

Solution for 90-20.8=c equation:

Simplifying
90 + -20.8 = c

Combine like terms: 90 + -20.8 = 69.2
69.2 = c

Solving
69.2 = c

Solving for variable 'c'.

Move all terms containing c to the left, all other terms to the right.

Add '-1c' to each side of the equation.
69.2 + -1c = c + -1c

Combine like terms: c + -1c = 0
69.2 + -1c = 0

Add '-69.2' to each side of the equation.
69.2 + -69.2 + -1c = 0 + -69.2

Combine like terms: 69.2 + -69.2 = 0.0
0.0 + -1c = 0 + -69.2
-1c = 0 + -69.2

Combine like terms: 0 + -69.2 = -69.2
-1c = -69.2

Divide each side by '-1'.
c = 69.2

Simplifying
c = 69.2