[tex]a) \frac{1}{9} + \frac{3}{7} = \frac{1 \times 7}{9 \times 7} + \frac{3 \times 9}{7 \times 9} = \frac{7}{63} + \frac{27}{63} = \frac{7 + 27}{63} = \frac{34}{63} [/tex]
[tex]b) \frac{1}{6} + \frac{3}{8} = \frac{1 \times 4}{6 \times 4} + \frac{3 \times 3}{8 \times 3} = \frac{4}{24} + \frac{9}{24} = \frac{4 + 9}{24} = \frac{13}{24} [/tex]
[tex]c) \frac{10}{39} + \frac{9}{117} = \frac{10 \times 3}{39 \times 3} + \frac{9}{117} = \frac{30}{117} + \frac{9}{117} = \frac{30 + 9}{117} = { \frac{39}{117} }^{(39} = \frac{1}{3} [/tex]
[tex]d) \frac{1}{2} + \frac{5}{4} = \frac{1 \times 2}{2 \times 2} + \frac{5}{4} = \frac{2}{4} + \frac{5}{4} = \frac{2 + 5}{4} = \frac{7}{4} = 1 \frac{3}{4} [/tex]
