What is 30 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 129 is 100%, so we can write it down as 129=100%.
4. We know, that x is 30% of the output value, so we can write it down as x=30%.
5. Now we have two simple equations:
1) 129=100%
2) x=30%
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:
129/x=100%/30%
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for what is 30% of 129

129/x=100/30
(129/x)*x=(100/30)*x       - we multiply both sides of the equation by x
129=3.33333333333*x       - we divide both sides of the equation by (3.33333333333) to get x
129/3.33333333333=x
38.7=x
x=38.7

now we have:
30% of 129=38.7