18% of what number is 43?

1. 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

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