we know that if 95 is out of 100%, we can write it down as 95 = 100%. we also know that x is 20% of the output value, so we can write it down as x = 20%.
now we have the equations:
95=100%
x=20%
next we will put the equations together
95/x = 100%/20%
95/x=100/20
(95/x)*x=(100/20)*x
we multiply both sides of the equation by x
95=5*x
now we divide both sides of the equation by 5 to get x
95/5=x
19=x
x=19
we now know that 20% of 95 = 19
let me know if you have any other questions
:)