578.9 is what percent of 645 - 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 645 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 645, so we can write it down as 100%=645.
4. We know, that x% equals 578.9 of the output value, so we can write it down as x%=578.9.
5. Now we have two simple equations:
1) 100%=645
2) x%=578.9
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%=645/578.9
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 578.9 is what percent of 645

100%/x%=645/578.9
(100/x)*x=(645/578.9)*x       - we multiply both sides of the equation by x
100=1.114182069442*x       - we divide both sides of the equation by (1.114182069442) to get x
100/1.114182069442=x
89.751937984496=x
x=89.751937984496

now we have:
578.9 is 89.751937984496% of 645