Bonsoir,
A = 7/4 - 1/8
A = (2 x 7)/(2 x 4) - 1/8
A = 14/8 - 1/8
A = 13/8
B = 1/8 + 11/24
B = (1 x 3)/(8 x 3) + 11/24
B = 3/24 + 11/24
B = 14/24
B = (2 x 7)/(2 x 12)
B = 7/12
C = 1/2 + 5/9
C = (1 x 9)/(2 x 9) + (5 x 2)/(9 x 2)
C = 9/18 + 10/18
C = 19/18
D = 13/5 - 11/4
D = (13 x 4)/(5 x 4) - (11 x 5)/(4 x 5)
D = 52/20 - 55/20
D = (-3/20)