39.6 is what percent of 640 - 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 640 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 640, so we can write it down as 100%=640.
4. We know, that x% equals 39.6 of the output value, so we can write it down as x%=39.6.
5. Now we have two simple equations:
1) 100%=640
2) x%=39.6
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%=640/39.6
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 39.6 is what percent of 640

100%/x%=640/39.6
(100/x)*x=(640/39.6)*x       - we multiply both sides of the equation by x
100=16.161616161616*x       - we divide both sides of the equation by (16.161616161616) to get x
100/16.161616161616=x
6.1875=x
x=6.1875

now we have:
39.6 is 6.1875% of 640