bonjour
A = - 12/7 + 5/14 = (-24+5)/14 = -19 /14
B = 8/35 + 6 / 15 = 8/35 + 2/5 = (8+14)/35 = 22/35
C = 23/26 - 12/39 = 23/26 - 4/13 = ( 23-8)/26 = 15/26
A = 63/30 * 60/-4 = 21/10 * - 15 = 315/10 = 63/2
B = 10/15 * 7/20 = 1/15 * 7/2 = 7/30
C = -5/12 * 18/13 = - 5/2 * 3/13 = -15/26
bonne journée ☺️