To get the solution, we are looking for, we need to point out what we know. 

1. We assume, that the number 95 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 95, so we can write it down as 100%=95. 
4. We know, that x% equals 38 of the output value, so we can write it down as x%=38. 
5. Now we have two simple equations:
1) 100%=95
2) x%=38
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:
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 38 is what percent of 95

(100/x)*x=(95/38)*x       – we multiply both sides of the equation by x
100=2.5*x       – we divide both sides of the equation by (2.5) to get x

now we have: 
38 is 40% of 95