644.5 is what percent of 900 - 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 900 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 900, so we can write it down as 100%=900.
4. We know, that x% equals 644.5 of the output value, so we can write it down as x%=644.5.
5. Now we have two simple equations:
1) 100%=900
2) x%=644.5
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%=900/644.5
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 644.5 is what percent of 900

100%/x%=900/644.5
(100/x)*x=(900/644.5)*x       - we multiply both sides of the equation by x
100=1.3964313421257*x       - we divide both sides of the equation by (1.3964313421257) to get x
100/1.3964313421257=x
71.611111111111=x
x=71.611111111111

now we have:
644.5 is 71.611111111111% of 900