What is 15 percent of 21.78 - 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 21.78 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 21.78 is 100%, so we can write it down as 21.78=100%.
4. We know, that x is 15% of the output value, so we can write it down as x=15%.
5. Now we have two simple equations:
1) 21.78=100%
2) x=15%
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:
21.78/x=100%/15%
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 15% of 21.78

21.78/x=100/15
(21.78/x)*x=(100/15)*x       - we multiply both sides of the equation by x
21.78=6.6666666666667*x       - we divide both sides of the equation by (6.6666666666667) to get x
21.78/6.6666666666667=x
3.267=x
x=3.267

now we have:
15% of 21.78=3.267