We assume, that the number 50 is 100% - because it's the output value of the task. <span>We assume, that x is the value we are looking for. </span>If 100% equals 50, so we can write it down as 100%=50. <span>We know, that x% equals 20 of the output value, so we can write it down as x%=20. </span>Now we have two simple equations: 1) 100%=50 2) x%=20 where left sides of both of them have the same units, and both right sides have the same units, so we can do something like that: 100%/x%=50/20 Now we just have to solve the simple equation, and we will get the solution we are looking for.
