To simplify the expression \( \frac{t^{400}}{t^{100}} \) using the Quotient Rule of Integer Exponents, you apply the rule which states:
\[ \frac{a^m}{a^n} = a^{m-n} \]
In this case, \( a = t \), \( m = 400 \), and \( n = 100 \). Applying the rule:
\[ \frac{t^{400}}{t^{100}} = t^{400 - 100} = t^{300} \]
Thus, the simplified expression is:
\[ t^{300} \]