18 is what percent of 421 - step by step solution

To get the solution, we are looking for, we need to point out what we know.

1. We assume, that the number 421 is 100% - because it's the output value of the task.
2. We assume, that x is the value we are looking for.
3. If 100% equals 421, so we can write it down as 100%=421.
4. We know, that x% equals 18 of the output value, so we can write it down as x%=18.
5. Now we have two simple equations:
1) 100%=421
2) 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%=421/18
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 18 is what percent of 421

100%/x%=421/18
(100/x)*x=(421/18)*x       - we multiply both sides of the equation by x
100=23.388888888889*x       - we divide both sides of the equation by (23.388888888889) to get x
100/23.388888888889=x
4.2755344418052=x
x=4.2755344418052

now we have:
18 is 4.2755344418052% of 421