Let's say x is the amount of money Kelly saves. We do not know how many weeks she is saving. If she was saving for 2, then the equation would be x=5(2). However, she is saving by w weeks, so the equation is x=5w.
I’m pretty sure you can make four if you’re distributing them evenly because they can both be decided by four so each kit would get 5 water bottles and 3 cans. I’m not 100% sure but lmk if it helped :)