39.78 is what percent of 221 - 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 221 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 221, so we can write it down as 100%=221.
4. We know, that x% equals 39.78 of the output value, so we can write it down as x%=39.78.
5. Now we have two simple equations:
1) 100%=221
2) x%=39.78
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%=221/39.78
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 39.78 is what percent of 221

100%/x%=221/39.78
(100/x)*x=(221/39.78)*x       - we multiply both sides of the equation by x
100=5.5555555555556*x       - we divide both sides of the equation by (5.5555555555556) to get x
100/5.5555555555556=x
18=x
x=18

now we have:
39.78 is 18% of 221