Răspuns:
Notăm cu g, p, respectiv o, cantitățile de grâu, porumb, orz.
\begin{gathered}\it g+p+o=55\ \ \ \ \ (1)\\ \\ g+p=42\ \ \ \ (2)\\ \\ p+o=40\ \ \ \ \ (3)\\ \\ (2),\ (3) \Rightarrow g+p+p+o=42+40 \Rightarrow g+p+o+p=82\ \ \ \ \ (4)\\ \\ (1),\ (4) \Rightarrow 55+p=82 \Rightarrow p=82-55 \Rightarrow p=27\ tone\\ \\ g+p=42 \Rightarrow g+27=42 \Rightarrow g=42-27 \Rightarrow g=15\ tone\\ \\ p+o=40 \Rightarrow 27+o=40 \Rightarrow o=40-27 \Rightarrow o=13\ tone\ .\end{gathered}
g+p+o=55 (1)
g+p=42 (2)
p+o=40 (3)
(2), (3)⇒g+p+p+o=42+40⇒g+p+o+p=82 (4)
(1), (4)⇒55+p=82⇒p=82−55⇒p=27 tone
g+p=42⇒g+27=42⇒g=42−27⇒g=15 tone
p+o=40⇒27+o=40⇒o=40−27⇒o=13 tone .
