[tex] \dfrac{3}{x^2+14x+48}\div\dfrac{3}{10x+60}=\dfrac{3}{x^2+8x+6x+48}\cdot\dfrac{10x+60}{3}\\\\=\dfrac{1}{x(x+8)+6(x+8)}\cdot\dfrac{10(x+6)}{1}=\dfrac{10(x+6)}{(x+6)(x+8)}=\dfrac{10}{x+8} [/tex]
Answer: C. [tex]\dfrac{10}{x+8}[/tex]
