\frac{(q; q_) a_{1} + a_{2} + \dots + a_{n}}{(q; q_) a_{1} (q; q_) a_{2} \dots (q; q_) a_{n}} = mbox c o e f f . o f x_{1}^{0} x_{2}^{0} \dots x_{n}^{0} mbox i n \prod_{1 \leq j < k \leq n} (\frac{x_{j}}{x_{k}}; q_) a_{j} (\frac{q x_{k}}{x_{j}}; q_) a_{k}