a)
[tex] \frac{7}{5} = \frac{7 \times 4}{5 \times 4} = \frac{28}{20} [/tex]
b)
[tex] \frac{7}{5} + \frac{9}{20} = \frac{28}{20} + \frac{9}{20} = \frac{37}{20} [/tex]
