51.2=128-r(128)

Solution for 51.2=128-r(128) equation:

Simplifying
51.2 = 128 + -1r(128)

Reorder the terms for easier multiplication:
51.2 = 128 + -1 * 128r

Multiply -1 * 128
51.2 = 128 + -128r

Solving
51.2 = 128 + -128r

Solving for variable 'r'.

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

Add '128r' to each side of the equation.
51.2 + 128r = 128 + -128r + 128r

Combine like terms: -128r + 128r = 0
51.2 + 128r = 128 + 0
51.2 + 128r = 128

Add '-51.2' to each side of the equation.
51.2 + -51.2 + 128r = 128 + -51.2

Combine like terms: 51.2 + -51.2 = 0.0
0.0 + 128r = 128 + -51.2
128r = 128 + -51.2

Combine like terms: 128 + -51.2 = 76.8
128r = 76.8

Divide each side by '128'.
r = 0.6

Simplifying
r = 0.6