How to solve this algebra problem!?

how would i go about solving this problem with a calculator. its in my algebra book and there are more like it, and idk how to solve them. Please help! thanks a bunch! :D
here it is: which is a better buy? A half pound of cashews for $2.93 or 3/4-pound bag for $4.19.
Update: Jared: yep, thats exactly how the book phrases it :P
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