90 is what percent of 643 - 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 643 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 643, so we can write it down as 100%=643.
4. We know, that x% equals 90 of the output value, so we can write it down as x%=90.
5. Now we have two simple equations:
1) 100%=643
2) x%=90
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%=643/90
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 90 is what percent of 643

100%/x%=643/90
(100/x)*x=(643/90)*x       - we multiply both sides of the equation by x
100=7.1444444444444*x       - we divide both sides of the equation by (7.1444444444444) to get x
100/7.1444444444444=x
13.996889580093=x
x=13.996889580093

now we have:
90 is 13.996889580093% of 643