21.5 is what percent of 280 - 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 280 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 280, so we can write it down as 100%=280.
4. We know, that x% equals 21.5 of the output value, so we can write it down as x%=21.5.
5. Now we have two simple equations:
1) 100%=280
2) x%=21.5
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%=280/21.5
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 21.5 is what percent of 280

100%/x%=280/21.5
(100/x)*x=(280/21.5)*x       - we multiply both sides of the equation by x
100=13.023255813953*x       - we divide both sides of the equation by (13.023255813953) to get x
100/13.023255813953=x
7.6785714285714=x
x=7.6785714285714

now we have:
21.5 is 7.6785714285714% of 280