Mike bought 49 bags, if he needs to have 328 bags in total how many more bags he needs to buy? show me how to do it

For this question, its 

Equation:
328(total) - 49 (what Mike already have) = 279 (needs to buy)

279 bags! I subtracted the number of bags he already had (49) by the number of bags he needed total (328) to get this difference (279). Another example of this same method would be, hm... I have 6 cats right now. I'd love to have 11. If I wanted to know how many more cats I needed to reach that number, I'd subtract the number of cats I wanted (11) by the number of cats I already have (6), which would leave me with 5 cats I needed to adopt. Make sense? Message me if you need any more help!