What is 20.21 percent of 642.5 - 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 642.5 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 642.5 is 100%, so we can write it down as 642.5=100%.
4. We know, that x is 20.21% of the output value, so we can write it down as x=20.21%.
5. Now we have two simple equations:
1) 642.5=100%
2) x=20.21%
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:
642.5/x=100%/20.21%
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for what is 20.21% of 642.5

642.5/x=100/20.21
(642.5/x)*x=(100/20.21)*x       - we multiply both sides of the equation by x
642.5=4.9480455220188*x       - we divide both sides of the equation by (4.9480455220188) to get x
642.5/4.9480455220188=x
129.84925=x
x=129.84925

now we have:
20.21% of 642.5=129.84925