18 is what percent of 39.9 - 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 39.9 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 39.9, so we can write it down as 100%=39.9.
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%=39.9
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%=39.9/18
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 39.9

100%/x%=39.9/18
(100/x)*x=(39.9/18)*x       - we multiply both sides of the equation by x
100=2.2166666666667*x       - we divide both sides of the equation by (2.2166666666667) to get x
100/2.2166666666667=x
45.112781954887=x
x=45.112781954887

now we have:
18 is 45.112781954887% of 39.9