87 is what percent of 3990 - 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 3990 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 3990, so we can write it down as 100%=3990.
4. We know, that x% equals 87 of the output value, so we can write it down as x%=87.
5. Now we have two simple equations:
1) 100%=3990
2) x%=87
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%=3990/87
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 87 is what percent of 3990

100%/x%=3990/87
(100/x)*x=(3990/87)*x       - we multiply both sides of the equation by x
100=45.862068965517*x       - we divide both sides of the equation by (45.862068965517) to get x
100/45.862068965517=x
2.1804511278195=x
x=2.1804511278195

now we have:
87 is 2.1804511278195% of 3990