①(5/6-1/4)X3/49÷3/4 ②题目我不写了。。
=(5/6X3/49-1/4X3/49)÷3/4 =5X8X0.125+5X4X0.25X10÷0.5
=(10/196-3/196)X4/3 = 5X1+5X1X10÷0.5
= 7/196X4/3 = 5+50÷0.5
=7/147 =5+25
=30
③=
![](https://iknow-pic.cdn.bcebos.com/7a899e510fb30f24faaef485ca95d143ad4b037b?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
④我不会简便算法,反正题目说喜欢什么方法都行
=(235+144612)X2005
————————————
145230-383
290598685
=——————
144847
满意望采纳~