21 is what percent of 1390 - 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 1390 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 1390, so we can write it down as 100%=1390.
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%=1390
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%=1390/21
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 1390

100%/x%=1390/21
(100/x)*x=(1390/21)*x       - we multiply both sides of the equation by x
100=66.190476190476*x       - we divide both sides of the equation by (66.190476190476) to get x
100/66.190476190476=x
1.5107913669065=x
x=1.5107913669065

now we have:
21 is 1.5107913669065% of 1390