What is 89.1 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 89.1% of the output value, so we can write it down as x=89.1%.
5. Now we have two simple equations:
1) 81=100%
2) x=89.1%
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%/89.1%
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 89.1% of 81

81/x=100/89.1
(81/x)*x=(100/89.1)*x       - we multiply both sides of the equation by x
81=1.1223344556678*x       - we divide both sides of the equation by (1.1223344556678) to get x
81/1.1223344556678=x
72.171=x
x=72.171

now we have:
89.1% of 81=72.171