66×45+22×65=22×135+22×65=22×（135+65）=22×200=4400
66×21＋19×21＋85×19＝(66＋19)×21＋85×19＝85×21＋85×19＝85×(21＋19)＝85×40＝17×(5×40)＝17×200＝3400
