81/450=.18 .18x100=18%

To get the solution, we are looking for, we need to point out what we know. 1. We assume, that the number 450 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 450, so we can write it down as 100%=450. 4. We know, that x% equals 81 of the output value, so we can write it down as x%=81. 5. Now we have two simple equations: 1) 100%=450 2) x%=81 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%=450/81 6. Now we just have to solve the simple equation, and we will get the solution we are looking for. 7. Solution for 81 is what percent of 450 100%/x%=450/81 (100/x)*x=(450/81)*x - we multiply both sides of the equation by x 100=5.55555555556*x - we divide both sides of the equation by (5.55555555556) to get x 100/5.55555555556=x 18=x x=18