We got the equation x/4 - 1/5 = 2.
(x/4) * 20 = 20x / 4 = 5x.
1/5 * 20 = 20/5 = 4.
2 * 20 = 40.
As you can see, when we multiply the terms of the equation by 20, we get the same equation as step 2.
So we multiplied both sides of the equation by 20.
Hope this helps! :D