a) Tính tổng: $2\frac{3}{4}+5\frac{7}{9}$.
Cách 1: $2\frac{3}{4}+5\frac{7}{9} = \frac{11}{4} + \frac{52}{9} = \frac{99}{36} + \frac{208}{36} = \frac{307}{36} = 8\frac{19}{36}$.
Cách 2: $2\frac{3}{4}+5\frac{7}{9} = 2\frac{27}{36} + 5\frac{28}{36} = 7\frac{55}{36} = 8\frac{19}{36}$.
b) Tính tổng: $7\frac{5}{6}-2\frac{9}{10}$.
Cách 1: $7\frac{5}{6}-2\frac{9}{10} = \frac{47}{6} - \frac{29}{10} = \frac{235}{30} - \frac{87}{30} = \frac{148}{30} = 4\frac{28}{30} = 4\frac{14}{15}$.
Cách 2: $7\frac{5}{6}-2\frac{9}{10} = 7\frac{25}{30} - 2\frac{27}{30} = 6\frac{55}{30} - 2\frac{27}{30} = 4\frac{28}{30} = 4\frac{14}{15}$.
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