66 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 66 of the output value, so we can write it down as x%=66.
5. Now we have two simple equations:
1) 100%=640
2) x%=66
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%=640/66
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 66 is what percent of 640

100%/x%=640/66
(100/x)*x=(640/66)*x       - we multiply both sides of the equation by x
100=9.6969696969697*x       - we divide both sides of the equation by (9.6969696969697) to get x
100/9.6969696969697=x
10.3125=x
x=10.3125

now we have:
66 is 10.3125% of 640