mr de m'aider il simplifier le résultat le plus possible mr

A = (1/9 - 1/7) x (7/3 - 1)
A = (1 x 7 / 9 x 7 - 1 x 9 / 7 x 9) x (7/3 - 1 x 3 / 1 x 3)
A = (7/63 - 9/63) x (7/3 - 3/3)
A = - 2/63 x - 4/3
A = 8/189

B = (1/3 + 5) + (5/24 - 1/15)
B = (1 x 40 / 3 x 40 + 5 x 120 / 1 x 120) + (5 x 5 / 24 x 5 - 1 x 8 / 15 x 8)
B = (40/120 + 600/120) + (25/120 - 8/120)
B = 640/120 + 17/120
B = 623/120