Răspuns :

2/5-4/3+1/2=12-40+15/30=-13/30
[1/9-15/9]:(13/3)=14/9*3/13=14/39


a) exercitiul devine

2/5-4/3+5/10=2/5-4/3+1/2

aducand la acelasi numitor ,30 ,avem

(12-40+15)/30=-13/30

         -2

b)[(-3)     -1,(6)]:13/3=[1:(-3)²   -(16-1):9]:13/3=(1/9-15/9)X3/13=-14/9X3/13=-14/39