21.3 is what percent of 639 - 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 639 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 639, so we can write it down as 100%=639.
4. We know, that x% equals 21.3 of the output value, so we can write it down as x%=21.3.
5. Now we have two simple equations:
1) 100%=639
2) x%=21.3
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%=639/21.3
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 21.3 is what percent of 639

100%/x%=639/21.3
(100/x)*x=(639/21.3)*x       - we multiply both sides of the equation by x
100=30*x       - we divide both sides of the equation by (30) to get x
100/30=x
3.3333333333333=x
x=3.3333333333333

now we have:
21.3 is 3.3333333333333% of 639