Answer:
Need more info
Step-by-step explanation:
You're working with rates. It's relatively straight forward. Take miles per hour for instance. If you travel 60 miles in one hour, you're rate of speed is 60 miles per hour.
You haven't given any data in this example but the idea is the same. Let's say he transferred 10 songs in 5 minutes. That's means his rate is 10 songs per 5 minutes. You can change that to a fraction so it's easier to understand:

Now just reduce the fraction and it becomes

Also known as 2 songs per minute
The answer is 20 days, we can solve this in following way:
Each friend creates 4 bags of dough and after ten days four bags divided into four more bags means:
3 friends x 4 bags = 12 bags and 12 bags x 4 = 48 bags
so in next 10 days, the 48 bags will be further divided into 4, so
48 x 4 = 192 bags
10 days + next 0 days = 20 days
so 20 days is the answer.
Why now :cccccccccccccccccc