[tex]\displaystyle \\
6) \\
\texttt{Aplicam regula de 3 simpla: } \\
23\% .................. 3220 ~tone~de~porumb \\
59\% .................. ~~~~x ~tone~de~grau \\ \\
x = \frac{59 \times 3220 }{23} = 59 \times 140 = \boxed{8260~tone~de~grau} \\ \\ \\ \\
7) \\
x * 1,2 * 1,15 = x + 760 \\\\
1,38 x - x = 760 \\
0,38 x = 760 \\
x = 760 / 0,38 = \boxed{2000 ~Lei~pretul~initial }\\
2000 * 1,2 = \boxed{2400 ~Lei~pretul~dupa~prima~scumpire }\\\\
Proba: \\
2400 * 1,15 = 2760 ~Lei~pretul~final[/tex]
