[tex]\frac{1}{27} + (\frac{7}{9} - \frac{2}{3} )[/tex] найти с нок.
[tex]42- 9\frac{3}{4} - (11\frac{7}{12} + 2\frac{5}{18})[/tex] найти с нок.
дроби к общему знаменателю.
[tex]\frac{8}{11}[/tex] и [tex]\frac{5}{8}[/tex]

[tex]\frac{7}{35}[/tex] и [tex]\frac{61}{63}[/tex]

ответ:

пошаговое объяснение:

1/27 + (7/9 - 2/3) = 4/27

1) 7/9 - 2/3 = [tex]\frac{7 * 1}{9 * 1}-\frac{2 * 3}{3 * 3}=[/tex] = 7/9 - 6/9 = 1/9

    9 = 3 * 3 * 1

    3 = 3 * 1

    нок (9 и 3) = 3 * 3 * 1 = 9  

    9 : 9 = 1

    9 : 3 = 3

2) 1/27 + 1/9 = [tex]\frac{1 * 1}{27 * 1}+\frac{1 * 3}{9 * 3}[/tex]=1/27 + 3/27 = 4/27

    27 = 3 * 3 * 3 * 1

    9 = 3 * 3 * 1

    нок (27 и 9) = 3 * 3 * 3 * 1 = 27

    27 : 27 = 1

    27 : 9 = 3

42 - 9 3/4 - (11 7/12 + 2 5/18) = 18 7/18

1) 11 7/12 + 2 5/18 = [tex]11\frac{7*3}{12*3} + 2\frac{5 * 2}{18*2}[/tex] = 11 21/36 + 2 10/36 = (11 + 2) + (21/36 + 10/36) = 13 31/36

  12 = 2 * 2 * 3 * 1

  18 = 2 * 3 * 3 * 1

  нок (12 и 18) = 2 * 2 * 3 * 3 * 1 = 36

  36 : 12 = 3

  36 : 18 = 2

2) 42 - 9 3/4 = 41 4/4 - 9 3/4 = 32 1/4

3) 32 1/4 - 13 31/36 = 32 9/36 - 13 31/36 = 31 45/36 - 13 31/36 = 18 14/36 = 18 7/18

8/11 и 5/8   =   64/88 и 55/88

11 = 11 * 1

8 = 2 * 2 * 2 * 1

нок (11 и 8) = 2 * 2 * 2 * 11 * 1 = 88

88 : 11 = 8

88 : 8 = 11

7/35 и 61/63 = 35/315 и 305/315

35 = 5 * 7 * 1

63 = 3 * 3 * 7 * 1

нок (35 и 63) = 5 * 7 * 3 * 3 * 1 = 315

315 : 35 = 9

315 : 63 = 5

sostavim proportiju:

3_ _ _ _16

15_ _ _ _x

x=15*16/3=80

otvet: 80 kg