641.2 is what percent of 820 - 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 820 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 820, so we can write it down as 100%=820.
4. We know, that x% equals 641.2 of the output value, so we can write it down as x%=641.2.
5. Now we have two simple equations:
1) 100%=820
2) x%=641.2
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%=820/641.2
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 641.2 is what percent of 820

100%/x%=820/641.2
(100/x)*x=(820/641.2)*x       - we multiply both sides of the equation by x
100=1.2788521522146*x       - we divide both sides of the equation by (1.2788521522146) to get x
100/1.2788521522146=x
78.19512195122=x
x=78.19512195122

now we have:
641.2 is 78.19512195122% of 820