8.6 is what percent of 21.5 - 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 21.5 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 21.5, so we can write it down as 100%=21.5.
4. We know, that x% equals 8.6 of the output value, so we can write it down as x%=8.6.
5. Now we have two simple equations:
1) 100%=21.5
2) x%=8.6
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%=21.5/8.6
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 8.6 is what percent of 21.5

100%/x%=21.5/8.6
(100/x)*x=(21.5/8.6)*x       - we multiply both sides of the equation by x
100=2.5*x       - we divide both sides of the equation by (2.5) to get x
100/2.5=x
40=x
x=40

now we have:
8.6 is 40% of 21.5