[tex]\displaystyle\bf\\1)\\\\\frac{1}{3a} +\frac{1}{2a} =\frac{1\cdot 2+1\cdot 3}{6a} =\frac{5}{6a} \\\\\\2)\\\\\frac{4}{4-y} -\frac{y}{y^{2} -16} =\frac{4}{4-y} -\frac{y}{(y-4)(y+4)} =\frac{4}{4-y} +\frac{y}{(4-y)(y+4)} =\\\\\\=\frac{4\cdot(y+4)+y}{(4-y)(y+4)} =\frac{4y+16+y}{(4-y)(y+4)}=\frac{5y+16}{16-y^{2} }[/tex]