Last friday tony worked 7 1/2 hours. express this time as a fraction of the day.

There are 60 minutes in one hour.  If I told you that Tony took 1/2 hour to finish his exercise, you'd know that 1/2 hour is 30 minutes.  You get that by multiplying 60 minutes by 1/2: (1/2)*(60 minutes) = 60/2 = 30 minutes.  

So if Tony took 7/10 of an hour to finish his exercise, that's 7/10 of 60 minutes:

(7/10)*(60 minutes) = 420/10 = 42 minutes

honeycrisps have skyrocketed to about $4.50 per pound