19. a) 3/5+0,2+(-6/10)+(+0,8)=
-3/5 + 2/10 -6/10 + 8/10. Amplifici -3/5 cu 2
-6/10+2/10-6/10+8/10 =
-6+2-6+8/10 =
-2/10 care se simplifica cu 2 =
-1/5
b) nu reusesc sa il rezolv
c)-3,75+(-1,5)+4,25+0,8(3)=
=-3,75-1,5+4,25+(83-8)/90=
=-5,25+4,25+5/6=
=-1+5/6=
=(-6+5)/6=-1/6
d)-3,5+2, (6)+(-0,25)+3 întregi 5/6=
=-35/10+(26-2)/9+(-1/4)+23/6=
=-7/2+24/9-1/4+23/6=
=-7/2+8/3-1/4+23/6=
=(-42+32-3+46)/12=
=33/12=
=11/4=2,75
20. a)5,95+1,52-0,6=7,47-0,6=6,87
b)5 întregi1/2-0,25+ 1/4-0,5
1:(2-0,25+1)=1:2,75
(5*1:2,75):(4-0,5)=5:2,75:3,5= 5:(2,75*3,5)= 5:9,62