B= 20 - 3 × 11 au carré +6
= 20 - 3 × 121 + 6
= 20 - 363 + 6
= - 343 + 6
= -337
C= 20 - 37 + 16 +6
= -17 + 22
= 5
D= 4/7 + 3/5
= 4×5/7×5 + 3×7/ 5×7
= 20/35 + 21/35
= 41/35
E= 4/7 × 3/5
= 12/35
F= 2/3 - 4/5 × 10/3
= 2/3 - 40/15
= 2×5/3×5 - 40×1/15×1
= 10/15 - 40/15
= 10-40/15
= -30/ 15
= -3×10/ 3×5
= -10/5
G= (3/4 - 1/2 )× 5/2-7/8
= 3×3/4×3 - 1×6/2×6 ×5/2 -7/8
= 9/12 - 6/12 × 5/2 - 7/8
= 3/12 × 5/2 -7/8
= 15/24 -7/8
= 15×1/ 24/1 - 7×3/8×3
= 15/24 - 21/24
=-6/24
= -3×2/ 3×8
= -2/8
