5. 3x450+[29318+(29318-9300)]-2x50=
=3x450+(29318+20018)-2x50=
=3x450+49336-2x50=
=1350+49336-100=
=50686-100=
=50586
6. (3x36)+(3x28)=108+84=192 lei sau 3x(36+28)= 3x64=192lei
7. 31x3=93 lei costa 31 mine pix
a). 31x2=62 lei costa 31 rezerve stilou
b). 93+62=155 lei costamine+rezerve