A = 7/3 - (2x8)/(11x3) = (11x7)/(11x3) - 16/(11x3) = (77+16)/33 = 93/33 = 31/11
B = (2x5)/(6x45) +7/9 = 2/(6x9) +7/9 car 45 = 9x5 on simplifie les 5
B = 2/54 + 7x6/(9x6) = 2/54 + 42/54 = 44/54 = 22/27
C = (4/(4x3)+5/12) x ( 3/9-5/9) = 9/12 x -2/9 = 3/4 - 2/9 = (3x9)/(4x9) - (2x4)/(4x9)
C = 27-8/36 = 19/36
D = 5x2/14 + 2/14 -9/14 = (10+2-9)/14 = 3/14
