It was a little unclear on what the question was overall asking for...
But here's what I came up with,
Since Lin earns $12 per hour, it will take her a total of 7 hours for her to have $84 so she can purchase her MP3 player.
Step-by-step explanation:
84 divided by 12 = 7 hours
Final Answer: It will take Lin a total of 7 hours to have the enough to purchase her MP3 player.
Hope this was found helpful for you!
It was my pleasure assisting you.