311.5 is what percent of 400 - 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 400 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 400, so we can write it down as 100%=400.
4. We know, that x% equals 311.5 of the output value, so we can write it down as x%=311.5.
5. Now we have two simple equations:
1) 100%=400
2) x%=311.5
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%=400/311.5
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 311.5 is what percent of 400

100%/x%=400/311.5
(100/x)*x=(400/311.5)*x       - we multiply both sides of the equation by x
100=1.2841091492777*x       - we divide both sides of the equation by (1.2841091492777) to get x
100/1.2841091492777=x
77.875=x
x=77.875

now we have:
311.5 is 77.875% of 400