90 is what percent of 138.5 - 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 138.5 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 138.5, so we can write it down as 100%=138.5.
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%=138.5
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%=138.5/90
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 138.5

100%/x%=138.5/90
(100/x)*x=(138.5/90)*x       - we multiply both sides of the equation by x
100=1.53888888889*x       - we divide both sides of the equation by (1.53888888889) to get x
100/1.53888888889=x
64.9819494585=x
x=64.9819494585

now we have:
90 is 64.9819494585% of 138.5