To simplify the expression \(\frac{k^{120}}{k^{30}}\), you can use the properties of exponents. Specifically, when dividing powers with the same base, you subtract the exponents:
\[ \frac{k^{120}}{k^{30}} = k^{120 - 30} = k^{90} \]
So, the simplified expression is:
\[ k^{90} \]