If you get a $1,000 loan at 1% interest each month, how much will you owe in 1 year?
You can buy a phone for $500 or pay Verizon $16.70 / month for 36 months. Which is cheaper?
Slightly off topic as I don't think this is college level algebra, in supermarkets in Europe they are required by law to put the "€/liter" price in small on the side, so you can compare easily. In the US it doesn't seem mandatory, or at least the unit is not mandatory because sometimes they use fl oz, sometimes gallons, or for pieces of meat sometimes oz, sometimes lbs, so when you want to compare the prices of 2 similar items, what would just take you 0.5 sec in Europe takes you much longer in the US since you need to add unit conversion in the mix. For example here your "cases" could be of different sizes, that 1 case of water could be 2L ,while those 3 cases could be a gallon each...
Yeah, and then you get aggregate price in "€/package", except that packages are of different size.
As for compound interest, you need WAY more than algebra ...
All of these are literally the sorts of things you'd find on homework assignments and final exams in a community college algebra course... You do need algebra, and don't realize how difficult this "trivial" algebra is for some students because you can do it without even realizing you're doing it.
I mean, there will be some FOIL and quadratic equation examples as well. And a bunch of stuff in-between like identifying graphs of functions.
But CC Algebra is super bimodal, so it's probably not the case that students are nailing these word problems and only failing with the other stuff.
Pe = nRT is actually the first thing taught in calc 1.