请教小学数学问题，求高手解答，要有详细步骤哦~

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=

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~

他说用你最喜欢的方法计算
你直接把答案写上，然后写我最喜欢的就是用计算器算