21 is what percent of 2580 - 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 2580 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 2580, so we can write it down as 100%=2580.
4. We know, that x% equals 21 of the output value, so we can write it down as x%=21.
5. Now we have two simple equations:
1) 100%=2580
2) x%=21
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:
100%/x%=2580/21
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 21 is what percent of 2580

100%/x%=2580/21
(100/x)*x=(2580/21)*x       - we multiply both sides of the equation by x
100=122.85714285714*x       - we divide both sides of the equation by (122.85714285714) to get x
100/122.85714285714=x
0.81395348837209=x
x=0.81395348837209

now we have:
21 is 0.81395348837209% of 2580