bonsoir
A = 15/7 - 11/2 * 7/3
A = 15/7 - 77/6
A = 90/42 - 539/42
A = - 449/90
B = 7/5 + 9/11 : 3 /4
B = 7/5 + 9/11 * 4/3
B = 7/5 + 36/33
B = 231/165 + 180/165
B = 411/165
b = 137 / 55
C = ( 8/5 + 5/6 ) : 23/12
C= ( 48/30 + 25/30 ) x 12/23
C = 73/30 x 12/33
C = 876 / 990
C = 146/ 165