C represents the number of four-packs of cartridges because the question says there are 4 pack of 42 ounceink cartridges that sell for 85.99...If you were ever to create an equation with this it would be 42c = 85.99 And you can plug in 4, 8, or 16 for c and check how much they would cost over all...your welcome, have a great day
Please let me know if you want me to add an explanation as to why this is the answer. I can definitely do that, I just don’t want to waste my time in case you don’t want me to :)