4(5x - 1) = 20x - 4
4(5x - 1)/4 = 20x/4 - 4/4
5x - 1 = 5x - 1
5x - 1 + 1 = 5x - 1 + 1
5x = 5x
5x/5 = 5x/5
x = x
The equation cannot be solved for x. It is simply an equation that, no matter how solved, will state x = x. In other words, x = all real numbers.