Answer:
Justin did not eat 7/12 of the pizza
Explanation:
Marc eats 1/6 × 24 = 4, 24 - 4 = 20 left over
Claudine eats 1/4 × 20= 5, 20 - 5 = 15 left over
Sylvia eats 1/3 × 15 = 5, 15 - 5 = 10 left over
Justin eats 10.
24 - 10 = 14
Justin did not eat 14/24 = 7/12