Bonsoir
a. 66/12 x 78/12 = 5 148/144 = (36 x 43) / (36 x 4) = 43/4
b. 28/9 x - 27/8 = - 756/72 = (36 x - 21) / (36 x 2) = - 21/2
c. - 26/- 8 x 14/8 = 364/64 = (4 x 91) / (4 x 16) = 91/16
d. 21/55 : 63/10 = 21/55 x 10/63 = 210/3 465 = (105 x 2) / (105 x 33) = 2/33
e. - 21 : - 63/15 = - 21 x - 15/63 = 315/63 = (63 x 5) / (63 x 1) = 5.
