12.9 is what percent of 80 - 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 80 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 80, so we can write it down as 100%=80.
4. We know, that x% equals 12.9 of the output value, so we can write it down as x%=12.9.
5. Now we have two simple equations:
1) 100%=80
2) x%=12.9
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:
100%/x%=80/12.9
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 12.9 is what percent of 80

100%/x%=80/12.9
(100/x)*x=(80/12.9)*x       - we multiply both sides of the equation by x
100=6.2015503875969*x       - we divide both sides of the equation by (6.2015503875969) to get x
100/6.2015503875969=x
16.125=x
x=16.125

now we have:
12.9 is 16.125% of 80