Joaquin buys 3 packs light bulbs. Each pack contains 12 light bulbs. After changing the bulbs in his house, he has 15 bulbs left. How many light bulbs did he use?

Sorry -- I was busy answering your other question.

Yes, he used 21 bulbs.

I'll be glad to check your answer.

kthanks i think its 21 is that true if not tell me what did i do wrong

ms sue u there???? well -____- i guess not

thank u

You're welcome.

To find out how many light bulbs Joaquin used, we need to subtract the number of bulbs he has left from the total number of bulbs he started with.

First, let's calculate the total number of light bulbs he had:
Joaquin bought 3 packs of light bulbs, and each pack contained 12 light bulbs.
So, the total number of bulbs he started with is 3 packs * 12 bulbs/pack = 36 bulbs.

Next, we subtract the number of bulbs he has left from the total number of bulbs to find how many he used:
Total bulbs - Bulbs left = Bulbs used
36 bulbs - 15 bulbs = 21 bulbs

Therefore, Joaquin used 21 light bulbs in his house.