( 5/6-5/粗雀9)×18/5 1÷(1-3/4×8/旅消9÷5/6)
=(5/6×18/51-5/9×18/51)÷(1-3/4×8/9×6/5)
=(5/17-10/51)÷(1-4/5)
=(15/51-10/51)÷1/5
=5/51×5
=25/51
19/20×[1÷(3/4+5/6)]
=19/20×[1÷19/12]
=19/20×12/19
=3/5
(4/7+8/岩镇早9)×2/25 此式没有简便运算
(4/7+8/9)×2/25
=4/7×2/25+8/9×2/25
=8/175+16/225
=184/1575
=4/7×2/25×9/9+8/9×2/25×7/7=184/1575