30-40。 The definition of grade five is that students in grade five of five-year system have to face junior high school exams. Aunt Zhang wants to send a 6 kg express to Chengdu, and the freight is 30-40. Express delivery, also known as express delivery or express delivery, refers to a new mode of transportation in which logistics enterprises (including freight forwarders) deliver documents or packages entrusted by users from the sender to the recipient quickly and safely through their own independent networks or in the form of joint ventures (i.e. networking).