621.5 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 621.5 of the output value, so we can write it down as x%=621.5.
5. Now we have two simple equations:
1) 100%=640
2) x%=621.5
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%=640/621.5
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 621.5 is what percent of 640

100%/x%=640/621.5
(100/x)*x=(640/621.5)*x       - we multiply both sides of the equation by x
100=1.0297666934835*x       - we divide both sides of the equation by (1.0297666934835) to get x
100/1.0297666934835=x
97.109375=x
x=97.109375

now we have:
621.5 is 97.109375% of 640