18 % of what number is 43

We assume that the number 43 is 100% because it's the output value of the task. Also that x is the value that we are looking for. So you write down

100% = 43

Next x% equals 18 of the output value. So you write it down as x% = 18

Now we have two simple equations which is 100%=43 and x%=18

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%=43/18

Now we just have to solve the simple equation. Solution for 18 is what percent of 43?

(100/x) * x = (43/18) * x - we multiply both sides of the equation by x

100=2.38888888889*x - we divide both sides of the equation by (2.38888888889) to get x

100/2.38888888889=x

41.86=x

x=41.86

Now we have: 18 is 41.86% of 43

239 is the answer to the problem