Длпоможіть будь ласка спростити вираз

[latex]( \frac{a+3}{a^2-1} - \frac{1}{a^2+a}): \frac{3a+3}{a^2-a} = ( \frac{a+3}{(a-1)(a+1)} - \frac{1}{a(a+1)}): \frac{3(a+1)}{a(a-1)} = [/latex][latex] \frac{a(a+3)-(a-1)}{a(a-1)(a+1)}* \frac{a(a-1)}{3(a+1)} = \frac{a^2+3a-a+1}{a+1}* \frac{1}{3(a+1)} = \frac{a^2+2a+1}{3(a+1)^2} = \frac{(a+1)^2}{3(a+1)^2} = \frac{1}{3} [/latex] Ответ: [latex] \frac{1}{3} [/latex]