-1/8+3/8x2/5=(simplificam 2 cu 8)=-1/8+3/20=aducem la acelasi numitor
numitor comun 40
prima se amplifica cu 5 a doua cu2
(-5+6)/40=1/40
3/7x7/9+1/2la 2=1/3+1/4=numitor comun 12
(4+3)/12=7/12
1/5x20/3-5/6:5=se simplifica 5 cu 20
4/3-5/6x1/5=se simpl 5 cu 5
4/3-1/6=numitor 6
(8-1)/6=7/6