Answer:
114
Step-by-step explanation:
Billy has to read more than 10 hours per week, which is equal to 1060=<<1060=600>>600 minutes.
Since it takes him 30 minutes to finish his first book, he has 600-30=<<600-30=570>>570 minutes left.
He needs to divide this time equally amongst the other 5 days, so he must read a minimum of 570/5=<<570/5=114>>114 minutes per day.