1.a)12-3+5          b)80 : 10 . 4       c)100 : 10 : 2        d)66 - 6 :2        e)12 + 8 . 4        f)34 + 66 : 6

   =9+5               =8x4                  =10 : 2                 =66 - 3             =12 + 32           =34 + 11

   =14                  =32                   =5                        =63                  =44                    =45

2.a)2 . 3 : 3 + 60 . 4 - 10 : 2             b)18 - 8 : (15 - 13)              c)50 - [( 20 - 8) : 2 + 4]

  = 6 : 3 + 240 - 5                           = 18 - 8 : 2                          =50 - [12 : 2 + 4]

  = 2 + 240 - 5                                = 18 - 4                               =50 - [6 + 4]

  =242 - 5                                       = 14                                     =50 - 10

  =237                                                                                         =40

  d)3500 - {50 . [(20 - 8) : 2 + 44]}           e)1727 + [6993 : 111 + (148 - 95) . 4 -2

  =3500 - {50 . [12 : 2 + 44}                     =1727 + [63 + 53 . 4 - 2]

  =3500 - {50 . [6 + 44]}                           =1727 + [63 + 212 - 2]

  =3500 - {50 . 50}                                    =1727 + [275 - 2]

  =3500 - 2500                                         =1727 + 273

  =1000                                                     =2000

  f)600 : {450 : [450 - (4 . 125 - 8 . 25)]}

  =600 : {450 : [450 - (500 - 200)]}

  =600 : {450 : [450 - 300]}

  =600 : {450 : 150}

  =600 : 3

  =200

3.a)21 . 6 + 18 . 6 + 6 . 61         

  =(21+18+61) . 6                      

  =100 . 6                                    

  =600                                        

  c)136 . 68 + 16 . 272

  =9248 + 4352

  =13 600

  d)49+27+87+53+51+13+71

  =(49+51)+(27+53)+(87+13)+71

  =100+80+100+71

  =351

  e)( 132 + 39 ) - 132

  =171 - 132

  = 39

  f)548 - (148 + 90)

  =548 - 238

  =310

  g)23 + 123 + 77 + 877

  =(23+877)+(123+77)

  =900 +200

  =1100

  h)25 . 122 . 4 . 10

  =25 . 4 . (122 . 10)

  =100 . 1220

  =122 000

  i)460:(5 . 23)

  =460 : 115

  =4

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