[tex]a) \frac{1}{5} + \frac{3}{6} = \frac{1}{5} + \frac{1}{2} = \frac{1 \times 2}{5 \times 2} + \frac{1 \times 5}{2 \times 5} = \frac{2}{10} + \frac{5}{10} = \frac{2 + 5}{10} = \frac{7}{10} [/tex]
[tex]b) \frac{5}{13} + \frac{2}{20} = \frac{5}{13} + \frac{1}{10} = \frac{5 \times 10}{13 \times 10} + \frac{1 \times 13}{10 \times 13} = \frac{50}{130} + \frac{13}{130} = \frac{50 + 13}{130} = \frac{63}{130} [/tex]
[tex]c) \frac{2}{8} + \frac{1}{4} = \frac{1}{4} + \frac{1}{4} = \frac{1 + 1}{4} = \frac{2}{4} = \frac{1}{2} [/tex]
[tex]d) \frac{6}{8} + \frac{4}{16} = \frac{3}{4} + \frac{1}{4} = \frac{3 + 1}{4} = \frac{4}{4} = 1 [/tex]
[tex]e) \frac{1}{3} + \frac{1}{2} + \frac{1}{8} = \frac{1 \times 8}{3 \times 8} + \frac{1 \times 12}{2 \times 12} + \frac{1 \times 3}{8 \times 3} = \frac{8}{24} + \frac{12}{24} + \frac{3}{24} = \frac{8 + 12 + 3}{24} = \frac{23}{24} [/tex]
