[tex]\displaystyle\bf\\\frac{5a+5b}{b} \cdot\frac{6b^{2} }{a^{2} -b^{2} } =\frac{5\cdot(a+b)}{b} \cdot\frac{b\cdot 6b}{(a+b)(a-b)} =\frac{5\cdot 6b}{a-b} =\frac{30b}{a-b}[/tex]