bonjour
a = 26/35 + 2/5 * ( 2/14 + 1/14)
a = 26/35 + 2/5 * 3/14
a = 26/35 + 6/20
a = 104/140 + 42/140
a = 146/140 = 73/70
b = ( 10/8 - 2/8) * ( 7/12 + 8/12)
b = 8/8 * 15/12 = 1 * 15/12 = 15/12 = 5/4
c = ( 12/15 - 5/15) * 6/15
c = 7/15 * 6/15
c = 42/225 = 14/75
