First, distribute the terms within each set of parentheses:

(5)(4) - (5)(x) - (2x)(4) + (2x)(x) - 2x(x) - 2x(6) = 1-x

Simplify each term:

20 - 5x - 8x + 2x^2 - 2x^2 - 12x = 1 - x

Combine like terms:

20 - 5x - 8x - 12x = 1 - x

Simplify further:

20 - 25x = 1 - x

Now, isolate x:

20 = 1 - x + 25x
20 = 1 + 24x
19 = 24x
x = 19/24

Therefore, x = 19/24.