Bonjour,
1)
A = -9/12 - 10/12 + 24/12 = 5/12
B = -75/ - 140 = 15/28
C= 14/15 * 1/7 = 14/ 105 =2/15
2)
A = 4/7 * -5/3 = - 20/21
B =
2+5/2 = 4/2 + 5/2 = 9/2
-3 (/ 9/2) = -3 * 2/9 = -6/9 = -2/3
C=
( -6/9 +4/9)/ 16/7
= -2/9 * 7/16 = -14/144 = -7/72
3)
A = -3 +2x
B= 12 - 18x
C= 8x² -24x -4 +3x
= 8x² -21x -4