27、 A transit company has a statistics table as follow showing how many days it takes to deliver packages.

Transit days No. of packages delivered

　　　1 　 10

　　 2　　　　　　　　　 9

　　　3　　　　　　　　 5

　　　4　　　　　　　　　 X

The average no. of transit days is 3 days, how many packages (x) need 4 days to deliver? Answer: 39

应是 29 吧！

我算的也是29

我也是29。