639.5 is what percent of 870 - 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 870 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 870, so we can write it down as 100%=870.
4. We know, that x% equals 639.5 of the output value, so we can write it down as x%=639.5.
5. Now we have two simple equations:
1) 100%=870
2) x%=639.5
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%=870/639.5
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 639.5 is what percent of 870

100%/x%=870/639.5
(100/x)*x=(870/639.5)*x       - we multiply both sides of the equation by x
100=1.3604378420641*x       - we divide both sides of the equation by (1.3604378420641) to get x
100/1.3604378420641=x
73.505747126437=x
x=73.505747126437

now we have:
639.5 is 73.505747126437% of 870