bonjour
a. 1/3 - 2/11 x 3 /7
= 1 /3 - 6/77
= 77/231 - 18/231
= 59/231
b . - 1/3 + ( 12 + 28) /21
= - 1/3 + 30 /21
= - 7/21 + 30 /21
= 23 /21
c. ( 2/5 - 3 ) : ( - 5 /2 + 4 )
= ( (2 - 15)/15 ) : ((- 5 + 8 )/2)
= - 13/15 : 3 /2
= - 13/15 x 2/3
= - 26 /45
d = - 44/20 + 25/20 - 270/20
= - 289/20
