21 is what percent of 7.9 - 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 7.9 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 7.9, so we can write it down as 100%=7.9.
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%=7.9
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%=7.9/21
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 7.9

100%/x%=7.9/21
(100/x)*x=(7.9/21)*x       - we multiply both sides of the equation by x
100=0.37619047619048*x       - we divide both sides of the equation by (0.37619047619048) to get x
100/0.37619047619048=x
265.82278481013=x
x=265.82278481013

now we have:
21 is 265.82278481013% of 7.9