Let's go through this step-by-step to find out how many chocolates Lucas originally had.

1. Determine the total number of chocolates shared:
   Each of the 9 friends received 5 chocolates, so: $9 \times 5 = 45$ Therefore, Lucas shared a total of 45 chocolates.

2. Account for the chocolates Lucas ate:
   Before sharing, Lucas ate 12 chocolates. This means that the total number of chocolates he had initially is the sum of the chocolates he shared and the ones he ate: $45 + 12 = 57$

Answer:

Lucas originally had 57 chocolates.

Would you like more details on this solution, or do you have any questions?

Here are 5 related questions to explore further:

1. If each friend had received 6 chocolates instead of 5, how many chocolates would Lucas have originally had?
2. What if Lucas ate 15 chocolates before sharing—how many would he have started with?
3. Suppose Lucas wanted to share the chocolates with 12 friends instead of 9; how would that affect the initial amount?
4. How many chocolates would each friend get if Lucas shared them with 10 friends and ate 12 before sharing?
5. If Lucas had shared the chocolates equally among 9 friends and kept 10 chocolates for himself, what was the initial count?

Tip: When working with word problems, list out each given quantity to help set up your equations clearly.