[tex]\it III)\ \ |-----|-----|-----|\rule{45}{0.8}|\\ \rule{0.2}{0.2}\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 5+7=12\\ \\ 12\cdot4=48\\ \\ II)\ \ |------|\rule{60}{0.8}|\\ \rule{0.2}{0.2}\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 2+48=50\\ \\ 50\cdot2=100\\ \\ I)\ \ |------|\rule{60}{0.8}|\rule{60}{0.8}|\\ \rule{0.2}{0.2}\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 4+100=104\\ \\ nr \ cai=104:2\cdot3=52\cdot3=156[/tex]