\( \begin{array}{ll}\text { a) } \frac{3}{5}=\frac{3 \times 7}{\cdots \cdots}=\frac{\cdots}{\cdots} & \text { e) } \frac{76}{12}=\frac{\cdots}{6}=\frac{19}{\cdots} \\ \text { b) } \frac{3}{4}=\frac{\cdots \cdots}{4 \times 15}=\frac{\cdots}{\cdots} & \text { f) } \frac{50}{100}=\frac{\cdots}{10}=\frac{1}{\cdots} \\ \text { c) } \frac{80}{100}=\frac{80 \div 20}{\cdots \cdots}=\frac{\cdots}{\cdots} & \text { g) } \frac{7}{5}=\frac{28}{\cdots}=\frac{\cdots}{100} \\ \text { d) } \frac{49}{49} \frac{49 \div \cdots}{\cdots} \frac{\cdots}{2} & \text { h) } \frac{16}{\cdots}\end{array} \)

To fill in the blanks, we can use proportionality and equivalent fractions. For instance, in the first fraction \( \frac{3}{5} \), multiplying both the numerator and the denominator by the same value (like 7) gives us \( \frac{3 \times 7}{5 \times 7} = \frac{21}{35} \). This means the blanks can be filled with \( 21 \) and \( 35 \). Now, let's consider \( \frac{76}{12} \). To convert that to have a denominator of 6, you can simplify \( \frac{76}{12} = \frac{38}{6} \) (by dividing both by 2). To find the other equivalent fraction, simply reduce \( \frac{76}{12} \) fully, leading to \( \frac{19}{3} \); thus, we fill in \( 19 \) and \( 3 \)!