What is 3.9 percent of 81 - 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 81 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 81 is 100%, so we can write it down as 81=100%.
4. We know, that x is 3.9% of the output value, so we can write it down as x=3.9%.
5. Now we have two simple equations:
1) 81=100%
2) x=3.9%
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:
81/x=100%/3.9%
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for what is 3.9% of 81

81/x=100/3.9
(81/x)*x=(100/3.9)*x       - we multiply both sides of the equation by x
81=25.641025641026*x       - we divide both sides of the equation by (25.641025641026) to get x
81/25.641025641026=x
3.159=x
x=3.159

now we have:
3.9% of 81=3.159