Answer:
Each pizza must be divided into 6 parts.   TRUE
Mario can feed 12 friends with 4 pizzas.  TRUE
Step-by-step explanation:
Total number of pizzas Mario has  = 4
Now the fraction of pizza eaten by 1 friend  = 2/6 = 1/3
⇒ 1 friend eats  of pizza.
 of pizza.
So, the fraction if pizza eaten by his 3 friends  = 3 x Fraction his 1 friend eats)

Hence, his 3 friends eats 1 complete pizza.
Now, he has a total of 4 pizzas.
So, the number of friends to finish 4 pizza  
= 4 x ( Number of people to finish 1 pizza) = 4 x 2  = 12 friends
Hence, his 12 friends eat 4 complete pizza.
Now, the given statements are:
Each pizza must be divided into 4 parts.
 False as 3 is NOT divisible by 4
Each pizza must be divided into 6 parts.   TRUE
Mario can feed 12 friends with 4 pizzas.  TRUE
Mario can feed 24 friends with 4 pizzas. FALSE