[tex]40 + 8 = 48 \: (nr. \: de \: vaci \: dupa \: cumparare)[/tex]
[tex]40 \: vaci \: ..... \: 60 \: zile \\ 48 \: vaci \: ..... \: x \: zile[/tex]
[tex] \frac{40}{48} = \frac{x}{60} [/tex]
[tex]x = \frac{40 \times 60}{48} = \frac{5 \times 60}{6} = 5 \times 10 = 50 \: zile[/tex]