Bonjour;
A= -2/21 x 14/5 - 8/5
= -28/105 -8/5
= -28/105 - 168/105
= -196/105
B= 1/4 + 5/3 x -1/8
= 1/4 -5/24
= 6/24 -5/24
= 1/24
C= 4/-3 + -7/6 x -2/5
= -4/3 +14/30
= -40/30+14/30
= -26/30 = -13/15
. D= ( 18/15 - 7/5) x ( -1/6 + 2/9)
= ( 18/15 -21/15) * ( -3/18 +4/18)
= -3/15 * 1/18
= -3/ 270 = -1/ 90