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Simplify the rational expressions, and identify any non-permissible values.

1. \(\frac{{\frac{{35pq}}{{r^2 }}}}{{\frac{{21p^2 }}{{qr}}}}\)
   
   


2. \(\frac{{3s + 7}}{{2\left( {s - 3} \right)}} \div \frac{5}{{s\left( {s - 3} \right)}}\)
   
   
   
3. \(\frac{{2t^2 + 11t + 5}}{{t^2 - 16}} \div \frac{{2t^2 + 3t + 1}}{{t^2 + t - 20}}\)