Final answer:
Milo initially has 5 rocks in his collection. After adding 40 more rocks, he has 45 rocks in total. Dividing this by 9 rocks per box, we find that he can fill exactly 5 boxes with no rocks left over.
Step-by-step explanation:
Milo starts with 5 rocks in his collection. He finds 40 more rocks outside to add to his collection, making the total number of rocks 5 + 40 = 45 rocks. To determine how many boxes of 9 rocks he will have, we need to divide the total number of rocks by the number of rocks per box.
Dividing 45 rocks by 9 rocks per box gives us:
45 ÷ 9 = 5 boxes
Therefore, Milo will have 5 full boxes of rocks, with no rocks left over since 45 is exactly divisible by 9.