13 is what percent of 129 - 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 129 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 129, so we can write it down as 100%=129.
4. We know, that x% equals 13 of the output value, so we can write it down as x%=13.
5. Now we have two simple equations:
1) 100%=129
2) x%=13
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%=129/13
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 13 is what percent of 129

100%/x%=129/13
(100/x)*x=(129/13)*x       - we multiply both sides of the equation by x
100=9.9230769230769*x       - we divide both sides of the equation by (9.9230769230769) to get x
100/9.9230769230769=x
10.077519379845=x
x=10.077519379845

now we have:
13 is 10.077519379845% of 129