Here's the question you clicked on:
Dumb_as_a_Duck
I've had problems understanding situations involving the mixture of substances that are already in a ratio. I can't work with two or more ratios. Here's an example sum that fails me - "There are three containers of equal capacity and all are completely filled with acid and water mixtures in different ratios. The ratio of acid to water in the first container is 2:3, in the second container is 3:7 and in the third container it is 4:11. If the mixtures of all the three containers are mixed together, what is the ratio of acid to water in it?"
See my video on allegation and mixture on http://www.youtube.com/katsageducation