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Răspuns :

Ex.26

1,8(3) - 7/5×x = [80%×x + 0,2(7)]/3

(183 - 18)/90 - 7x/5 = [80/100 × x + (27-2)/90]/3

165/90 - 7x/5 = (4x/5 + 25/90)/3

11/6 - 7x/5 = (4x/5 + 5/18)/3

(11/6 - 7x/5) × 3 = 4x/5 + 5/18

11/2 - 21x/5 = 4x/5 + 5/18

11/2 - 5/18 = 4x/5 + 21x/5

99/18 - 5/18 = 25x/5

94/18 = 5x

47/9 = 5x

x = 47/9 : 5 = 47/9 × 1/5

x = 47/45 = 1,0(4)

Ex.27

2/3 × [0,1(6) + 3x/8] = 75% × x - 1,7(2)

2/3 × [(16-1)/90 + 3x/8] = x×75/100 - (172-17)/90

2/3 × (15/90 + 3x/8) = 3x/4 - 155/90

2/3 × (1/6 + 3x/8) = 3x/4 - 31/18

1/9 + x/4 = 3x/4 - 31/18

1/9 + 31/18 = 3x/4 - x/4

2/18 + 31/18 = 2x/4

33/18 = x/2

x = 33/18 × 2

x = 33/9 = 3,(6)