Bonjour
a. 3/9 + 5/2 = (3 x 2) / (9 x 2) + (5 x 9) / (2 x 9) = 6/18 + 45/18 = 51/18 = (3 x 17) / (3 x 6) = 17/6
b. 6/7 - 2/3 = (6 x 3) / (7 x 3) - (2 x 7) / (3 x 7) = 18/21 - 14/21 = 4/21
c. 7/4 - 9/5 = (7 x 5) / (4 x 5) - (9 x 4) / (5 x 4) = 35/20 - 36/20 = - 1/20
d. 3/8 + 1/7 = (3 x 7) / (8 x 7) + (1 x 8) / (7 x 8) = 21/56 + 8/56 = 29/56
e. - 7/3 + - 1/4 = (- 7 x 4) / (3 x 4) - (1 x 3) / (4 x 3) = - 28/12 - 3/12 = - 31/12
f. 2/11 - 3/10 = (2 x 10) / (11 x 10) - (3 x 11) / (10 x 11) = 20/110 - 33/100 = - 13/110.
