[tex]a\to prima \ zi \\\\ 2a\to a \ doua \ zi \\\\ 2*2a=4a\to a \ treia \ zi \\\\ 2*4a=8a\to a \ patra \ zi \\\\ 2*8a=16a\toa \ cincea \ zi \\\\\\ a+2a+4a+8a+16a=1767 \\\\ 31a=1767 \ \ \ |:31 \\\\ \boxed{a=57 \ frunze \ au \ cazut \ in \ prima \ zi}[/tex]