What is 5 percent of 399.9 - 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 399.9 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 399.9 is 100%, so we can write it down as 399.9=100%.
4. We know, that x is 5% of the output value, so we can write it down as x=5%.
5. Now we have two simple equations:
1) 399.9=100%
2) x=5%
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:
399.9/x=100%/5%
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 5% of 399.9

399.9/x=100/5
(399.9/x)*x=(100/5)*x       - we multiply both sides of the equation by x
399.9=20*x       - we divide both sides of the equation by (20) to get x
399.9/20=x
19.995=x
x=19.995

now we have:
5% of 399.9=19.995