39.9 is what percent of 57 - 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 57 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 57, so we can write it down as 100%=57.
4. We know, that x% equals 39.9 of the output value, so we can write it down as x%=39.9.
5. Now we have two simple equations:
1) 100%=57
2) x%=39.9
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%=57/39.9
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 39.9 is what percent of 57

100%/x%=57/39.9
(100/x)*x=(57/39.9)*x       - we multiply both sides of the equation by x
100=1.4285714285714*x       - we divide both sides of the equation by (1.4285714285714) to get x
100/1.4285714285714=x
70=x
x=70

now we have:
39.9 is 70% of 57