12. Efectuați:
a) (7/8 + 1/8) + 1/4 ;
b) (5/6 + 7/6) - 1/7 ;
c) (7/3 - 4/3) - 12/13 ;
d) 4/3 - (9/11 + 2/11) .
REPEDE + COROANA
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