Write each expression in a simpler form by using the smallest base. (The answer will not always be in $p^q$ form.)

1. $6^{2} · 36^{−3} · 216^{0}$

   Hint (a):

   $216^{\large\circ} =1$

   Answer (a):

   $6^{-4}$

2. $\frac { 25 ^ { 2 } \cdot 5 ^ { - 3 } } { 125 ^ { - 2 } }$

   Hint (b):

   Convert all the bases to $5$.

3. $\left(3 · 19^{97}\right) ÷ \left(8 · 19^{94}\right)$

   Answer (c):

   $\frac{3\cdot19^{97}}{8\cdot 19^{94}}=$

   $\frac{3}{8} \cdot 19^{97-94}=$

   $\frac{3}{8} \cdot 19^3$

4. $\left(3 · 19^{−97}\right) ÷ \left(8 · 19^{−94}\right)$

   Hint (d):

   Follow the same process as (c).