\[a\left(1-\frac{b}{c}\right){{}_{2}\phi_{1}}\left({a,b/q\atop c};q,z\right)-b%
\left(1-\frac{a}{c}\right){{}_{2}\phi_{1}}\left({a/q,b\atop c};q,z\right)=(a-b%
)\left(1-\frac{abz}{cq}\right){{}_{2}\phi_{1}}\left({a,b\atop c};q,z\right),\]