0.4 is what percent of 3.12 - 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 3.12 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 3.12, so we can write it down as 100%=3.12.
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%=3.12
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%=3.12/0.4
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 3.12

100%/x%=3.12/0.4
(100/x)*x=(3.12/0.4)*x       - we multiply both sides of the equation by x
100=7.8*x       - we divide both sides of the equation by (7.8) to get x
100/7.8=x
12.820512820513=x
x=12.820512820513

now we have:
0.4 is 12.820512820513% of 3.12