Answer:
You can purchase 10 songs after buying 12 videos.
Explanation:
Step 1 - Find out how much downloading a video costs. If the cost of a video download is 5 times as much as a song download costs, and a song download is $1, then you'd have to multiply 5 x $1, which equals 5. So downloading a video costs $5.
Step 2 - Find how much it costs to buy 12 videos by multiplying the cost of 1 video to how many you bought, 12. We already found out 1 video costs $5, so that would 12 x $5, which equals $60. That means those 12 video downloads costed you $60 dollars.
Step 3 - Find out how many songs you can buy with your remaining credit. If you already payed $60 dollars worth of videos, then you only have $10 dollars left to spend because $70 - $60 is $10. So if every song costs $1 dollar, then you'd be able to purchase 10 more songs until you reach your credit, $70 dollars.