so he bought 9 lbs of fruit
he paid 2.39 a lb for 5 lbs.....thats 2.39 * 5 = 11.95
and now he has (9 - 5) = 4 lbs remaining...that he paid 1.99 per lb....thats is (1.99 * 4) = 7.96
for a total of : 11.95 + 7.96 = 19.91 <==
u can basically set it up like this : total cost = 2.39(5) + 1.99(4)