Question

What per cent of : 80 m is 36 m ?

Answer 1

36/80×100=45%
36m is 45% of 80m

Answer 2

1. We assume, that the number 36 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 36 is 100%, so we can write it down as 36=100%. 
4. We know, that x is 80% of the output value, so we can write it down as x=80%. 
5. Now we have two simple equations:
1) 36=100%
2) x=80%
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:
36/x=100%/80%
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 80% of 36

36/x=100/80
(36/x)*x=(100/80)*x       - we multiply both sides of the equation by x
36=1.25*x       - we divide both sides of the equation by (1.25) to get x
36/1.25=x 
28.8=x 
x=28.8m

now we have: 
80% of 36=28.8m