The first 60 megabytes take 60/5=<<60/5=12>>12 seconds.

There are 90-60=<<90-60=30>>30 remaining megabytes.

The remaining 30 megabytes take 30/10=<<30/10=3>>3 seconds.

And 12+3=<<12+3=15>>15 seconds.

# Answer

15
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
The file, 90 megabytes in size, downloads at the rate of 5 megabytes per second for its first 60 megabytes, and then 10 megabytes per second thereafter. How long, in seconds, does it take to download entirely?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
15
The file, 90 megabytes in size, downloads at the rate of 5 megabytes per second for its first 60 megabytes, and then 10 megabytes per second thereafter. How long, in seconds, does it take to download entirely?
train