What is 86.4 percent of 90 - 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 90 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 90 is 100%, so we can write it down as 90=100%.
4. We know, that x is 86.4% of the output value, so we can write it down as x=86.4%.
5. Now we have two simple equations:
1) 90=100%
2) x=86.4%
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:
90/x=100%/86.4%
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 86.4% of 90

90/x=100/86.4
(90/x)*x=(100/86.4)*x       - we multiply both sides of the equation by x
90=1.1574074074074*x       - we divide both sides of the equation by (1.1574074074074) to get x
90/1.1574074074074=x
77.76=x
x=77.76

now we have:
86.4% of 90=77.76