bonjour
-2/3-[-1/6-(-2/3-4/7+1/2)-(3/2-1/6)]
= - 2/3 - [ - 1/6 - ( - 28/42 - 24/42 + 21/42 ) - ( 9/6 - 1 /6 ) ]
= - 2/3 - [ - 1 /6 - ( - 31 /42 ) - ( 8 /6 )]
= - 2 /3 - ( - 1 /6 + 31/42 - 8 /6 )
= - 2/3 - ( - 7/42 + 31/42 - 56/42 )
= - 28/ 42 - ( - 32 / 42 )
= - 28/42 + 32 /42
= 4/42
= 2/21
