Alright.. so the operations would be multiplication and addition. The reason for this is you're finding the amount the school got --24*8-- and the amount the homeroom got --24*3-- then add those to get the total he got.
Let's use the variable 't' to represent the total he collected. We know that the school gets 8 for every book and he sold 24, so this can be represented with 8*24. We also know that the homeroom gets 3 for every book, so 3*24. Both of these added will give you the total amount of money he earned, 't'. So the sentence can be written as t=8(24)+3(24). t=192+72. t=264. So, we can see that the total he earned was $264. If you look back at the equation, we know that the 8*24 represents the amount the school earned, which means that school earned $192. The same goes with the amount the homeroom earned; we know that this is represented by 3*24, and thus the homeroom earned $72. And that's it!!! (:
