[tex]\displaystyle\bf\\1)\\\\\frac{x(b+7)}{y(b+7)} =\frac{x}{y} \\\\\\2)\\\\\frac{5(m-3)^{3} }{(m-3)^{4} } =\frac{5(m-3)^{3} }{(m-3)\cdot(m-3)^{3} } =\frac{5}{m-3} \\\\\\3)\\\\\frac{a^{2} y(x-2)^{2} }{ay(x-2)} =\frac{ay\cdot a\cdot(x-2)\cdot(x-2)}{ay\cdot(x-2)} =a(x-2)\\\\\\4)\\\\\frac{12x^{3}(y-7) }{16x^{2} (y-7)^{2} } =\frac{4x^{2} \cdot 3x\cdot(y-7)}{4x^{2} \cdot 4\cdot(y-7)\cdot(y-7)} =\frac{3x}{4(y-7)}[/tex]