[tex]a)\\1/5+2/3\\\\=\frac{1}{5}+2/3\\\\=\frac{1}{5}+\frac{2}{3}\\\\=\frac{13}{15}[/tex]
[tex]b)\\7/2\cdot \:2/3\\\\=\frac{7}{2}\cdot \:2/3\\\\=7/3\\\\=\frac{7}{3}\\\\=2\frac{1}{3}[/tex]
[tex]c)\\3/5\div \left(8/5-4/5\right)\\\\=3/5\div \frac{4}{5}\\\\=\frac{3}{4}[/tex]
[tex]d)\\-23+72-1/6\\\\=-23+72-\frac{1}{6}\\\\=\frac{293}{6}\\\\=48\frac{5}{6}[/tex]
[tex]e)\\5/4\div \:1/3\\\\=\frac{5}{4}\div \:1/3\\\\=\frac{5}{4}/3\\\\=\frac{5}{12}[/tex]
[tex]f)\\-1/5\left(8/3-3\right)\\\\-1/5\left(8/3-3\right)\\\\=\frac{1}{15}[/tex]
[tex]g)\\7\div \:1/4\\\\=7/4\\\\=\frac{7}{4}\\\\=1\frac{3}{4}[/tex]
[tex]h)\\3+\left[1/12-3/2\left(7/2-5/3\right)-3/4\right]\\\\=1/12-3/2\cdot \frac{11}{6}-3/4\\\\=\frac{1}{12}-3/2\cdot \frac{11}{6}-3/4\\\\=\frac{1}{12}-\frac{11}{4}-3/4\\\\\frac{1}{12}-\frac{11}{4}-\frac{3}{4}\\\\=-\frac{41}{12}\\\\=3-\frac{41}{12}\\\\3-\frac{41}{12}\\\\=-\frac{5}{12}\\\\---\\\\=-\frac{5}{12}[/tex]