4.2 is what percent of 31.8 - 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 31.8 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 31.8, so we can write it down as 100%=31.8.
4. We know, that x% equals 4.2 of the output value, so we can write it down as x%=4.2.
5. Now we have two simple equations:
1) 100%=31.8
2) x%=4.2
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%=31.8/4.2
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 4.2 is what percent of 31.8

100%/x%=31.8/4.2
(100/x)*x=(31.8/4.2)*x       - we multiply both sides of the equation by x
100=7.5714285714286*x       - we divide both sides of the equation by (7.5714285714286) to get x
100/7.5714285714286=x
13.207547169811=x
x=13.207547169811

now we have:
4.2 is 13.207547169811% of 31.8