[tex]\it 2)\ 4,5\ell =4,5kg=4500g\\ \\ \\ c\%=\dfrac{500}{4500+500}\cdot100=\dfrac{500}{5000}\cdot100 =\dfrac{50000}{5000} =10\%[/tex]
[tex]\it 3)\ |x-3| +(y+1)^2 =0 \Rightarrow \begin{cases}\it x-3=0 \Rightarrow x=3\\ \\ \it y+1=0 \Rightarrow y=-1 \end{cases}\\ \\ x+y=3+(-1) =3-1=2[/tex]
[tex]\it 4)\ \ Vom\ nota\ d-\ lungimea\ drumului.\\ \\ \dfrac{5}{5}-\dfrac{2}{5}=\dfrac{3}{5}\ din\ drum\ mai\ are\ de\ parcurs.\\ \\ \\ \dfrac{3}{5}\ din\ d\ =\ 180 \Rightarrow \dfrac{3}{5}\cdot\ d=180 \Rightarrow d=180\cdot\dfrac{5}{3} =60\cdot5=300\ km.[/tex]
