Question

6bags of plaster do 33m squared, how many metre squared can be done with 5bag

Answer 1

6 bags of plaster do 33m squared
1 bag of plaster do 33/6 m squared
5 bags of plaster do 33*5/6 m squared
= 27.5 m squared

So your answer is 27.5 m squared

Answer 2

ratio and proportion

6/33= 5/x
cross multiply
6x= 165
x= 27 1/2 m^2 with 5 bags

Hope this helps