640.72 is what percent of 780 - 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 780 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 780, so we can write it down as 100%=780.
4. We know, that x% equals 640.72 of the output value, so we can write it down as x%=640.72.
5. Now we have two simple equations:
1) 100%=780
2) x%=640.72
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%=780/640.72
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 640.72 is what percent of 780

100%/x%=780/640.72
(100/x)*x=(780/640.72)*x       - we multiply both sides of the equation by x
100=1.2173804469971*x       - we divide both sides of the equation by (1.2173804469971) to get x
100/1.2173804469971=x
82.14358974359=x
x=82.14358974359

now we have:
640.72 is 82.14358974359% of 780