40 is what percent of 1991 - 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 1991 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 1991, so we can write it down as 100%=1991.
4. We know, that x% equals 40 of the output value, so we can write it down as x%=40.
5. Now we have two simple equations:
1) 100%=1991
2) x%=40
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%=1991/40
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 40 is what percent of 1991

100%/x%=1991/40
(100/x)*x=(1991/40)*x       - we multiply both sides of the equation by x
100=49.775*x       - we divide both sides of the equation by (49.775) to get x
100/49.775=x
2.0090406830738=x
x=2.0090406830738

now we have:
40 is 2.0090406830738% of 1991