80 is what percent of 644 - 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 644 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 644, so we can write it down as 100%=644.
4. We know, that x% equals 80 of the output value, so we can write it down as x%=80.
5. Now we have two simple equations:
1) 100%=644
2) x%=80
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%=644/80
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 80 is what percent of 644

100%/x%=644/80
(100/x)*x=(644/80)*x       - we multiply both sides of the equation by x
100=8.05*x       - we divide both sides of the equation by (8.05) to get x
100/8.05=x
12.422360248447=x
x=12.422360248447

now we have:
80 is 12.422360248447% of 644