4) \(\frac{11}{5} - \frac{13}{4} = \frac{44}{20} - \frac{65}{20} = -\frac{21}{20} = -1\frac{1}{20}\)
9) \(\frac{7}{5} + \frac{1}{20} = \frac{28}{20} + \frac{1}{20} = \frac{29}{20} = 1\frac{9}{20}\)