En détaillant les étapes,calculer chacune des expressions suivantes. A=1/6-3/8 B=25/36:-10/9 C=2/3+1/3*7/4

1/6 - 3/8
= (1 x 4)/(6 x 4) - (3 x 3)/(8 x 3)
= 4/24 - 9/24
= - 5/24

25/36 : (- 10/9)
= 25/36 x (- 9/10)
= - (5 x 5 x 9)/(9 x 4 x 2 x 5)
= - 5/8

2/3 + 1/3 x 7/4
= 2/3 + 7/12
= (2 x 4)/(3 x 4) + 7/12
= 8/12 + 7/12
= 15/12
= (3 x 5)/(3 x 4)
= 5/4

A = 1/6 - 3/8
   = 1×4/6×4 - 3×3/8×3
   = 4/24 - 9/24
   = -5/24

B = 25/36 ÷ -10/9
   = 25/36 × 10/9
   = 25×10/36×9
   = 250/324
   = 250÷2/324÷2
   = 125/162

C = 2/3 + 1/3 ×7/4
   = 2/3 + 1×7/3×4
   = 2/3 + 7/12
   = 2×4/3×4 + 7/12
   = 8/12 + 7/12
   = 15/12
   = 15÷3/12÷3
   = 5/4