Bonsoir
A= -3/2+5/2
A = 2/2
A = 1
B=(-2/3 - -4/9) : (5/2 + 1/2 * 3/-7)
B = [(- 2 x 3) / (3 x 3) + 4/9] : (5/2 - 3/14)
B = (- 6/9 + 4/9) : [(5 x 7) / (2 x 7) - 3/14]
B = - 2/9 : (35/14 - 3/14)
B = - 2/9 : 32/14
B = - 2/9 x 14/32
B = - 28/28/288
B = (4 x - 7) / (4 x 72)
B = - 7/72.