Answer: 100 seats are next to a window.
Step-by-step explanation: 1. We assume, that the number 500 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 500 is 100%, so we can write it down as 500=100%.
4. We know, that x is 20% of the output value, so we can write it down as x=20%.
5. Now we have two simple equations:
1) 500=100%
2) x=20%
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:
500/x=100%/20%
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.
7. Solution for what is 20% of 500
500/x=100/20
(500/x)*x=(100/20)*x - we multiply both sides of the equation by x
500=5*x - we divide both sides of the equation by (5) to get x
500/5=x
100=x
x=100
now we have:
20% of 500=100