亲,满意就采纳吧
18×29-19×12=18x29-(29-10)x12=18x29-12x29+120=29x(18-12)+120=29x6+120=174+120=294
(≧▽≦)
18x29-19x12=18x(30-1)-(20-1)x12=540-18-240+12=300-6=294