21 is what percent of 85 - 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 85 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 85, so we can write it down as 100%=85.
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%=85
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%=85/21
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 85

100%/x%=85/21
(100/x)*x=(85/21)*x       - we multiply both sides of the equation by x
100=4.04761904762*x       - we divide both sides of the equation by (4.04761904762) to get x
100/4.04761904762=x
24.7058823529=x
x=24.7058823529

now we have:
21 is 24.7058823529% of 85