Verified answer

Bonsoir,

1)

A = 1 - 1/3 - 1/4 x 2/5

A = 1 - 1/3 - 2/20

A = 1 - 1/3 - 1/10

A = (1 x 30) / (1 x 30) - (1 x 10) / (3 x 10) - (1 x 3) / (10 x 3)

A = 30/30 - 10/30 - 3/30

A = 17/30

B = (1 - 1/3 - 1/4) x 2/5

B = [(1 x 12) / (1 x 12) - (1 x 4) / (3 x 4) - (1 x 3) / (4 x 3)] x 2/5

B = (12/12 - 4/12 - 3/12) x 2/5

B = 5/12 x 2/5

B = 10/60

B = (10 x 1) / (10 x 6)

B = 1/6

C = (1 - 1/3 - 1/4) : 2/5

C = (12/12 - 4/12 - 3/12) : 2/5

C = 5/12 : 2/5

C = 5/12 x 5/2

C = 25/24

D = 1 - (1/3 + 1/4) x 2/5

D = 1 - (4/12 + 3/12) x 2/5

D = 1 - 7/12 x 2/5

D = (1 x 60) / (1 x 60) - 14/60

D = 60/60 - 14/60

D = 46/60

D = (2 x 23) / (2 x 30)

D = 23/30

2)

1 - (1/3 + 1/4)

= 12/12 - (4/12 + 3/12)

= 12/12 - 7/12

= 5/12

Après que les deux 1ers se soient servis il reste 5/12 de chocolat

5/12 x 2/5 = 10/60 = (10 x 1) / (10 x 6) = 1/6

Le 3eme prend 1/6 du chocolat.

La B.