For pepperoni pizza, Abe wants 1/2, while Becca wants 2/3, which is a total of 1/2 + 2/3 = 3/6 + 4/6 = 7/6 = 1 and 1/6. Therefore at least 2 pepperoni pizzas are needed.
For cheese pizza, Cam was 2/4 = 1/2, while Kim wants 2/6 = 1/3. This is a total of 1/2 + 1/3 = 3/6 + 2/6 = 5/6. Therefore just 1 cheese pizza will be enough.
The total number of pizzas that must be ordered is 2 + 1 = 3.