80 is what 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 100% equals 81, so we can write it down as 100%=81.
4. We know, that x% equals 80 of the output value, so we can write it down as x%=80.
5. Now we have two simple equations:
1) 100%=81
2) x%=80
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%=81/80
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 80 is what percent of 81

100%/x%=81/80
(100/x)*x=(81/80)*x       - we multiply both sides of the equation by x
100=1.0125*x       - we divide both sides of the equation by (1.0125) to get x
100/1.0125=x
98.765432098765=x
x=98.765432098765

now we have:
80 is 98.765432098765% of 81