After a brief bout of problem solving the six inch slice has more surface area, yes, but what if they had made the problem more complicated by switching the prices?

Interestingly enough, if the six inch slice was $1.70 and the seven inch slice Costa $1.50, each would cost about 27 cents per square inch, with negligible price point difference.

However, adjusting the prices so that both cost the same per square inch doesn't solve the real problem; how do we get the most pizza?

The answer is simple.

Buy both slices.