21 is what percent of 64 - 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 64 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 64, so we can write it down as 100%=64.
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%=64
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%=64/21
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 64

100%/x%=64/21
(100/x)*x=(64/21)*x       - we multiply both sides of the equation by x
100=3.047619047619*x       - we divide both sides of the equation by (3.047619047619) to get x
100/3.047619047619=x
32.8125=x
x=32.8125

now we have:
21 is 32.8125% of 64