(158+120÷6)×5=(158+20)x5=178x5=180x5-2x5=900-10=890就按照顺序去算 就可以了
(158+120÷6)×5的简便运算=(158+20)x5=178x5=180x5-2x5=900-10=890
(158 +120÷6)×5=(158+20)x10÷2=1780÷2=890
