观察下列算式：1×5+4=3²，2×6+4=4²，3×7+4=5²，4×8+4=6²，请你在观察规律之后并用你得到的规律填空：____×____ +____=50²．

Dear sir ,
   I have travel every day from Souk Road to the airport. Two buses travel along the routes: the(路线): the number 49 and the number 16. But by the time the number 16 bus reaches Souk Road, it is always full, so I can’t get on it, I have to wait for the number 49 because sometimes there are empty seats on it.
   The timetable says that there are buses from Souk Road to the airport every ten minutes. If this is true, why do I have to wait half an hour for a bus nearly every day?
   The rules say that if there are empty seats on a bus, the bus must stop at every stop where people are waiting Why do the half-empty buses go straight(一直)past me when I am standing at bus stop?
   The rules say that no bus may carry more than 40 seated passengers and 20 standing passengers. Yesterday I was the first to get off the bus when it reached the airport. I counted the other passengers as they got off. There were 129 people.
It is clear that our bus companies break the rules and think little of their passengers. Can nothing be done to make your service(服务) better?
                                                                                                          Yours
                                                                                               Tired passenger