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Пошаговое объяснение:

А)

1) -0,2 * 0,3 = -0,06

2) -0,06 - 0,1 = -0,16

3) -4,9 : (-0,16) = 30,625

Б)

1) 3. 17/36 - 6. 7/12 = 3. 17/36 - 6. 21/36 = -3. 4/36 = -3. 1/9

2) -3. 1/9 : 0,4 = -3. 1/9 : 4/10 = -28/9 * 10/4 = -7/9 * 10/1 = -70/9 = -7. 7/9

3) 4. 1/3 : (-0,65) = 4. 1/3 : (-65/100) = 13/3 : (-13/20) = 13/3 * (-20/13) = -20/3 = -6. 2/3

4) -7. 7/9 + (-6. 2/3) = -7. 7/9 - 6. 2/3 = -7. 7/9 - 6. 6/9 = -13. 13/9 = -14. 4/9

В)

1) 49 * (-45) = -2205

2) 2 * (-3) = -6

3) 84 - (-6) = 84 + 6 = 90

4) -14 * 90 = -1260

5) -2205 : (-1260) = 1,75

Г)

1) -4. 3/7 - 1. 2/3 = -4. 9/21 - 1. 14/21 = -5. 23/21 = -6. 2/21

2) -6. 2/21 * 2,1 = -6. 2/21 * 2. 1/10 = -128/21 * 21/10 = -128/10 = -12,8

3) 18 - 2,64 = 15,36

4) 15,36 : (-1. 3/5) = 15,36 : (-8/5) = 15,36 : (-1,6) = -9,6

5) -12,8 : (-9,6) = -12. 8/10 : (-9. 6/10) = -128/10 : (-96/10) = -128/10 * (-10/96) = 128/96 = 1. 32/96 = 1. 1/3

В решении.

Пошаговое объяснение:

Сразу по действиям:

1.

1) -0,2 * 0,3 = -0,06;

2) -0,06 - 0,1 = -0,16;

3) -4,9 : (-0,16) = 30,625;

2.

1) 3 17/36 - 6 7/12 = -(6 21/36 - 3 17/36) = -3 4/36 = -3 1/9;

2) -3 1/9 : 0,4 = -28/9 : 2/5 = -(28 * 5)/(9 * 2) = -70/9;

3) 4 1/3 : (-0,65) = 13/3 : (-13/20) = -(13 * 20)/(3 * 13) = -20/3;

4) -70/9 - 20/3 = -(70 + 60)/9 = -130/9 = -14 4/9.

3.

1) 49 * (-45) = -2205;

2) 2 * (-3) = -6;

3) 84 - (-6) = 84 + 6 = 90;

4) -14 * 90 = -1260;

5) -2205 : -1260 = 1,75.

Или: (быстрее):

1) 2 * (-3) = -6;

2) 84 - (-6) = 84 + 6 = 90;

3) (49 * (-45))/(-14 * 90) =

сократить 49 и -14 на 7; -45 и 90 на 45;

= (7 * (-1))/(-2 * 2) = -7/-4 = 1,75.

4.

1) -4 3/7 - 1 2/3 = -(4 9/21 + 1 14/21) = -5 23/21 = -6 2/21;

2) -6 2/21 * 2,1 = -128/21 * 2,1 = -128/10 = -12,8;

3) 18 - 2,64 = 15,36;

4) 15,36 : (-8/3) = 15 9/25 : (-8/3) = 384/25 * (-8/3) = -(48 * 3)/25 =

= -144/25 = -5,76.

5) -12,8 : (-5,76) = -12 4/5 : (-5 19/25) =

= -64/5 : (-144/25) = (64 * 25)/(5 * 144) = 20/9 = 2 2/9.