1. We assume, that the number 80 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 80 is 100%, so we can write it down as 80=100%.
4. We know, that x is 12.5% of the output value, so we can write it down as x=12.5%.
5. Now we have two simple equations:
1) 80=100%
2) x=12.5%
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:
80/x=100%/12.5%
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 12.5% of 80
80/x=100/12.5
(80/x)*x=(100/12.5)*x - we multiply both sides of the equation by x
80=8*x - we divide both sides of the equation by (8) to get x
80/8=x
10=x
x=10
now we have:
12.5% of 80=10