[tex]\displaystyle\bf\\1)\\\\\frac{5x-15y}{5x} =\frac{5\cdot(x-3y)}{5x} =\frac{x-3y}{x} \\\\2)\\\\\frac{6y^{2} -36y}{12-2y} =\frac{6y\cdot(y-6)}{2\cdot(6-y)} =-3y\\\\3)\\\\\frac{d^{2} -4}{d^{2} -4d+4} =\frac{d^{2}-2^{2} }{d^{2}-2\cdot d\cdot 2+2^{2} } =\\\\\\=\frac{(d-2)\cdot(d+2)}{(d-2)^{2} } =\frac{d+2}{d-2} \\\\\\4)\\\\\frac{ab-6a-3b+18}{36-b^{2} } =\frac{(ab-6a)-(3b-18)}{6^{2} -b^{2} } =\\\\\\=\frac{a\cdot(b-6)-3\cdot(b-6)}{(6-b)(6+b)} =\frac{(b-6)\cdot(a-3)}{(6-b)\cdot(6+b)} =[/tex]

[tex]\displaystyle\bf\\=\frac{3-a}{b+6}[/tex]