bonjour

Réponse:

a. x/3 = x/4 - 6/5

X/3-X/4 = -6/5

4/12x-3/12x = -6/5

1/12x = -6/5

x = -6/5 *12

x = -6*12/5

x = - 72/5

b. 5x/8 - 3/10 = 7x / 40

5/8x -7/40x = 3/10

25/40x -7/40x=3/10

18/40 x =3/10

x=3/10*40/18

X = 120/180

x =12/18

x = 2/3

c. 2x/7+3/14 = x/7 - 1/14

2/7x -1/7x = -1/14 -3/14

1/7x=-4/14

1/7x = -2/7 x = -2/7 x 7

x =-14/7

x = -2

d. 2/5 x - 1/9 = 3/9 x + 4/5

2/5x -3/9x = 4/5 +1/9 18/45x -15/45 x = 36/45 +5/45

3/45x = 41/45 1/15x =41/45

x = 41/45 *15

x = 41/3

ps: quand il y a marqué .../.... c'est une fraction