[tex]\it a\ \ |\rule{40}{0.8} |\underbrace{\rule{40}{0.8} |\rule{40}{0.8} |\rule{40}{0.8}|}_{sc\breve adem}\\ \\ \rule{0.2}{0.2}\ \ \ \ |\rule{40}{0.8}|=7\\ \\ \\ a=4\times 7=28[/tex]
