A 3-pack of light bulbs costs $3.45. A 4-pack if the same light bulbs costs $4.20. Which pack is the better value.

The 4 pack is better

Explained: if you divide 4 by 4.20 you find that each bulb in the pack costs 1.05 but if you divide 3.45 by 3 you find each bulb costs 1.12 therefore the 4 pack is a better value