[tex]a) \frac{2}{5} + \frac{3}{10} = \frac{2 \times 2}{5 \times 2} + \frac{3}{10} = \frac{4}{10} + \frac{3}{10} = \frac{4 + 3}{10} = \frac{7}{10} [/tex]
[tex]b) \frac{2}{9} + \frac{2}{3} = \frac{2}{9} + \frac{2 \times 3}{3 \times 3} = \frac{2}{9} + \frac{6}{9} = \frac{2 + 6}{9} = \frac{8}{9} [/tex]
[tex]c) \frac{3}{4} + \frac{5}{8} = \frac{3 \times 2}{4 \times 2} + \frac{5}{8} = \frac{6}{8} + \frac{5}{8} = \frac{6 + 5}{8} = \frac{11}{8} = 1 \frac{3}{8} [/tex]
[tex]d) \frac{7}{8} + \frac{1}{2} = \frac{7}{8} + \frac{1 \times 4}{2 \times 4} = \frac{7}{8} + \frac{4}{8} = \frac{7 + 4}{8} = \frac{11}{8} = 1 \frac{3}{8} [/tex]
[tex]e) \frac{1}{2} + \frac{1}{4} = \frac{1 \times 2}{2 \times 2} + \frac{1}{4} = \frac{2}{4} + \frac{1}{4} = \frac{2 + 1}{4} = \frac{3}{4} [/tex]
[tex]f) \frac{3}{10} + \frac{2}{5} = \frac{3}{10} + \frac{2 \times 2}{5 \times 2} = \frac{3}{10} + \frac{4}{10} = \frac{3 + 4}{10} = \frac{7}{10} [/tex]
[tex]g) \frac{1}{6} + \frac{2}{3} = \frac{1}{6} + \frac{2 \times 2}{3 \times 2} = \frac{1}{6} + \frac{4}{6} = \frac{1 + 4}{6} = \frac{5}{6} [/tex]
[tex]h) \frac{3}{5} + \frac{1}{20} = \frac{3 \times 4}{5 \times 4} + \frac{1}{20} = \frac{12}{20} + \frac{1}{20} = \frac{12 + 1}{20} = \frac{13}{20} [/tex]
