May i know under what circumstances we have to use the comparison method? Tks

Hi Mandy, noticed that after drawing 3 units for non fiction and 5 units for fiction and reading 6 for non fiction and 13 for fiction, you are not able to cut equal units for non fiction and fiction from the original model. So you have to use unit/ parts method. It’s more difficult to understand but if you master it, it will help you to solve this type of questions easily.

Thank u for ur explanation