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?
##Solution## 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.
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