90 is what percent of 210 - 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 210 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 210, so we can write it down as 100%=210.
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%=210
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%=210/90
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 210

100%/x%=210/90
(100/x)*x=(210/90)*x       - we multiply both sides of the equation by x
100=2.3333333333333*x       - we divide both sides of the equation by (2.3333333333333) to get x
100/2.3333333333333=x
42.857142857143=x
x=42.857142857143

now we have:
90 is 42.857142857143% of 210