Pg 648 (580) - Q24
The total time it takes to trim a set of trees is the product of
the # of trees times the trimming time per tree. Find the total time
for each set of trees, and then add up the separate totals to get a final
total. Make sure to divide by 60 to convert the time from
minutes to hours. So, (7*20 + 8*40 + 10*80 + 15*100) ÷
60 is 46 hours.