[tex]\displaystyle\\
x = \text{pretul initial}\\\\
x - 20\% \cdot x = x(1 - 20\%) = x \cdot 80\% = \boxed{\bf0,8x}~\text{dupa prima ieftinire} \\\\
0,8x - 10\%\cdot 0,8x=0,8x(1 - 10\%)= \\
= 0,8x \cdot 90\% = 0,8x \cdot 0,9 = \boxed{\bf 0,9\cdot 0,8x}~\text{dupa a doua ieftinire} \\\\
\text{Scriem ecuatia:}\\\\
0,9\cdot 0,8x = 720 \\\\
0,72 x = 720\\\\
x = \frac{720}{0,72}=\boxed{\boxed{\bf 1000~Lei }}~~\texttt{pretul initial} [/tex]
