Bonjour
38)
A = 13/25 - 2/5 = 13/25 - (2 x 5) / (5 x 5) = 13/25 - 10/25 = 3/25
B = 31/18 - 4/3 = - 31/18 - (4 x 6) / (3 x 6) = - 31/18 - 24/18 = - 55/18
C = 1 - 5/42 = (1 x 42) / (1 x 42) - 5/42 = 42/42 - 5/42 = 37/42
39)
A = 5/2 + 3/4 + - 7/8
A = (5 x 4) / (2 x 4) + (3 x 2) / (4 x 2) - 7/8
A = 20/8 + 6/8 - 7/8
A = 26/8 - 7/8
A = 19/8
B = 4/15 + 2/5 - 7/30
B = (4 x 2) / (15 x 2) + (2 x 6) / (5 x 6) - 7/30
B = 8/30 + 12/30 - 7/30
B = 20/30 - 7/30
B = 13/30.
