bonjour
a = 7x 8/49 = 7 x 8/7x7 = 8/7
b = 54/45 x5 = 54/9x5 x 5 = 54/9 = 6
c = 3/5 x 65/33 = 3/5 x 13x5 /3x11 = 13/11
d = 39/25 x 15/13 = 13x3 / 5x5 x 5x3/13 =3/5x3 = 9/5
e = 465/126 x 294/105 = 15x31 /42x3 x 42x7 /15x7 = 15x31 /42x3 x 42/15 = 31/3
f = 56/63 x 17/40 x 54/51 = 8x7 /9x7 x 17/4x10 x 54/17x3 = 8/9 x 1/4x10 x 54/3
f =4x2/9 x 1/4x10 x18
f = 2/9x1/10 x 18
f = 2 x1/10 x2
f = 4/10
f = 2/5