20.5 is what percent of 405 - 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 405 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 405, so we can write it down as 100%=405.
4. We know, that x% equals 20.5 of the output value, so we can write it down as x%=20.5.
5. Now we have two simple equations:
1) 100%=405
2) x%=20.5
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%=405/20.5
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 20.5 is what percent of 405

100%/x%=405/20.5
(100/x)*x=(405/20.5)*x       - we multiply both sides of the equation by x
100=19.756097560976*x       - we divide both sides of the equation by (19.756097560976) to get x
100/19.756097560976=x
5.0617283950617=x
x=5.0617283950617

now we have:
20.5 is 5.0617283950617% of 405