5.107 Вычислите. a) 53 – 46 . 7 + 31 – 45 : 7 ? б) 520 + 280 : 20 . 5 : 25 . 125 ? в) 63 – 57 . 6 + 34 – 30 : 8 ? г) 600 – 120 : 4 . 2 : 5 . 20 ? д) 81 – 73 . 8 + 26 – 58 : 8 ?

Выполним вычисления по действиям:

1. а) 53 – 46

         53
       -46
       ---
         7
       

   7 . 7 = 49

         7
       x 7
       ---
        49
       

   49 + 31 = 80

        49
       +31
       ---
        80
       

   80 – 45 = 35

        80
       -45
       ---
        35
       

   35 : 7 = 5

2. б) 520 + 280 = 800

        520
       +280
       -----
        800
       

   800 : 20 = 40

        800 | 20
       -80  | --
       ---  | 40
         00
         -0
         --
         0
       

   40 . 5 = 200

        40
       x 5
       ---
       200
       

   200 : 25 = 8

        200 | 25
       -200 | --
       ---- |  8
          0
       

   8 . 125 = 1000

        125
       x  8
       ----
       1000
       

3. в) 63 – 57 = 6

        63
       -57
       ---
        6
       

   6 . 6 = 36

         6
       x 6
       ---
        36
       

   36 + 34 = 70

        36
       +34
       ---
        70
       

   70 – 30 = 40

        70
       -30
       ---
        40
       

   40 : 8 = 5

        40 | 8
       -40 |--
       --- | 5
         0
       

4. г) 600 – 120 = 480

        600
       -120
       -----
        480
       

   480 : 4 = 120

        480 | 4
       -4   | ---
       ---  | 120
         08
        - 8
         --
          00
          -0
          --
          0
       

   120 . 2 = 240

        120
       x  2
       ----
        240
       

   240 : 5 = 48

        240 | 5
       -20  | ---
       ---  | 48
         40
        -40
        ---
          0
       

   48 . 20 = 960

        48
       x20
       ---
       960
       

5. д) 81 – 73 = 8

        81
       -73
       ---
        8
       

   8 . 8 = 64

        8
       x8
       ---
       64
       

   64 + 26 = 90

        64
       +26
       ---
        90
       

   90 – 58 = 32

        90
       -58
       ---
        32
       

   32 : 8 = 4

        32 | 8
       -32 |--
       --- | 4
         0
       

Ответ: а) 5; б) 1000; в) 5; г) 960; д) 4.