Question 4432
Multiply both sides of the equation by the LCD, which in this case is 20.  This step clears out all the fractions.

{{{x/4 - 1 = x/5}}}

{{{20 * (x/4) - 20*1 = 20*( x/5)}}}

{{{5x - 20 = 4x}}} 


Add -5x to each side:
{{{5x - 5x - 20 = 4x - 5x}}}

{{{-20 = -x}}}


Divide both sides by -1, and you get 
{{{20 = x}}}


R^2 at SCC