SVP c'est juste super urgent !!

c = 8/3 - 2/3 × 8/7
c = 8/3 - 16/21
c = 56/21 - 16/21
c = 40/21

d = ( - 2/5 + 5/2 ) × ( - 3/4 + 1/2 )
d = ( - 4/10 + 25/10 ) × ( - 3/4 + 2/4 )
d = 21/10 × ( - 1/4 ) 
d = - 21/40