Question

Jaoquin buys 3 dozen lightbulbs. After changing the lightbulbs in his house, he has 15 lightbulbs left. How many lightbulbs did he use? Explain your work. I need the help like right now!!

Answer 1

dozen = 12
12 x 3 = 36

36 light bulbs in total
15 left

so 36 - 15 = 21

answer = 21

Answer 2

Well, you know that 1 dozen = 12 items so if you have 3 dozen, that means 12 x 3 = 36 Set up an equation: 36 + x = 15 solve for x which represents the amount he used.