Bonjour svp svp pouvez vous m'aider à faire cette exercice et merci d'avance. ​

Bonjour

a. 21/45 + 28/60

= (3 x 7) / (3 x 15) + (4 x 7)  /(4 x 15)

= 7/15 + 7/15

= 14/15

b. 26/12 + 3/18

= (2 x 13) / (2 x 6) + (3 x 1) / (3 x 6)

= 13/6 + 1/6

= 14/6

= (2 x 7) / (2 x 3)

= 7/3

c. 78/40 + 75/100

= (2 x 39) / (2 x 20) + (25 x 3) / (25 x 4)

= 39/20 + (3 x 5) / (4 x 5)

= 39/20 + 15/20

= 54/20

= (2 x 27) / (2 x 10) = 27/10

Réponse :

Bonjour

Explications étape par étape

A = 21/45 + 28/60   on simplifie les fractions

A =  (3 X 7) / 3 X 15) + (4 X 7)/ (4 X 15)

A = 7/15 + 7/15

A = 14/15

B = 26/12 +3/18

B = 26/12 X 18/18 + 3/18 X 12/12

B = 468/216 + 36/216

B = 504/216 divisible par 9

B = 56/24 = 28/12 = 14/6 = 7/3

C = 78/40 +75/100

C = 2 X 39/ 2 X 20 + 25 X 3 / 25 X 4

C = 39/20 + (3 X 5) / 4 X 5

C = 39/20 + 15/20

C = 54/20 = 27/10