A pack of 6 cans of pop costs £1.80. A pack of 10 cans of pop costs £3.50.
Which one should you buy?

Let us look at the cost per can of both packs.

Cost of can in 6-pack = 1.80/6

                                      = £0.30

Cost of can in 10-pack = 3.50/10

                                     = £0.35

Since the cost of a can in the 6-pack is cheaper, it would be better to buy the 6-pack if you were looking to save money.