To simplify the expression \((7^{-3})^7 \cdot \frac{7^{20}}{6^{-2}}\) and generate equivalent expressions with only positive exponents, we can use the properties of integer exponents.
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Apply the power of a power property:
\[ (7^{-3})^7 = 7^{-3 \cdot 7} = 7^{-21} \]
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Next, we rewrite the expression:
\[ 7^{-21} \cdot \frac{7^{20}}{6^{-2}} \]
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Rewrite the denominator with positive exponents:
\(6^{-2} = \frac{1}{6^2}\), therefore:
\[ \frac{7^{20}}{6^{-2}} = 7^{20} \cdot 6^2 \]
This allows us to rewrite the whole expression:
\[ 7^{-21} \cdot 7^{20} \cdot 6^2 \]
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Combine the powers of \(7\):
\[ 7^{-21 + 20} \cdot 6^2 = 7^{-1} \cdot 6^2 \]
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Changing \(7^{-1}\) to positive exponent:
\[ 7^{-1} = \frac{1}{7} \]
Therefore, the expression is:
\[ \frac{1}{7} \cdot 6^2 \]
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Calculate \(6^2\):
\[ 6^2 = 36 \]
So, we have:
\[ \frac{1}{7} \cdot 36 = \frac{36}{7} \]
Thus, the final answer is:
\[ \frac{36}{7} \]
This is the expression simplified with only positive exponents, and the answer in improper fraction form is:
\[ \boxed{\frac{36}{7}} \]