0.4 is what percent of 8.7 - 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 8.7 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 8.7, so we can write it down as 100%=8.7.
4. We know, that x% equals 0.4 of the output value, so we can write it down as x%=0.4.
5. Now we have two simple equations:
1) 100%=8.7
2) x%=0.4
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%=8.7/0.4
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 0.4 is what percent of 8.7

100%/x%=8.7/0.4
(100/x)*x=(8.7/0.4)*x       - we multiply both sides of the equation by x
100=21.75*x       - we divide both sides of the equation by (21.75) to get x
100/21.75=x
4.5977011494253=x
x=4.5977011494253

now we have:
0.4 is 4.5977011494253% of 8.7