bonsoir

A  = ( 4/10 - 3 /10) x 2/3

= 1/10 x 2/3

= 2/30 = 1 /15

B =  6/20 - 3/10 x 1/2

= 6/20 - 3/20

= 3/20

3/20 > 1.15

Réponse:

A=1/15 B=3/20

Explications étape par étape:

A=(2×2/5×2 - 3/10)×2/3

A=(4/10 - 3/10) × 2/3

A=1/10 × 2/3

A=1×3/10×3 × 2×10/3×10

A=3/30 × 20/30

A=3×2×2×5

3×2×5×3×2×5

A=1/15

B=2/5×3/4-3/10:2

B=2×4/5×4 × 3×5/4×5 -3/10:2

B=8/20 × 15/20 - 3/10 :2

B=2×2×2×3×5 - 3/10:2

2×2×5×2×2×5

B=3/10-3/10:2

B=3/10- 3 ×1

10× 2

B=3×2/10×2 - 3/20

B=6/20-3/20

B=3/20