1. We assume, that the number 106 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 106, so we can write it down as 100%=106.
4. We know, that x% equals 115 of the output value, so we can write it down as x%=115.
5. Now we have two simple equations:
1) 100%=106
2) x%=115
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%=106/115
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 115 is what percent of 106

100%/x%=106/115
(100/x)*x=(106/115)*x – we multiply both sides of the equation by x
100=0.92173913043478*x – we divide both sides of the equation by (0.92173913043478) to get x
100/0.92173913043478=x
108.49056603774=x
x=108.49056603774

now we have:
115 is 108.49056603774% of 106