What is 80 percent of 21.3 - 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 21.3 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 21.3 is 100%, so we can write it down as 21.3=100%.
4. We know, that x is 80% of the output value, so we can write it down as x=80%.
5. Now we have two simple equations:
1) 21.3=100%
2) x=80%
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:
21.3/x=100%/80%
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 80% of 21.3

21.3/x=100/80
(21.3/x)*x=(100/80)*x       - we multiply both sides of the equation by x
21.3=1.25*x       - we divide both sides of the equation by (1.25) to get x
21.3/1.25=x
17.04=x
x=17.04

now we have:
80% of 21.3=17.04