Вычислить: a) $$20 \frac{17}{37} + 14 \frac{12}{37} + 31 \frac{8}{37}$$ б) $$150 - 149 \frac{149}{150}$$ в) $$6 \frac{5}{8}$$ г) $$12 \frac{7}{9}$$

a) $$20 \frac{17}{37} + 14 \frac{12}{37} + 31 \frac{8}{37} = (20+14+31) + (\frac{17}{37} + \frac{12}{37} + \frac{8}{37}) = 65 + \frac{17+12+8}{37} = 65 + \frac{37}{37} = 65 + 1 = 66$$ б) $$150 - 149 \frac{149}{150} = 150 - (149 + \frac{149}{150}) = 150 - 149 - \frac{149}{150} = 1 - \frac{149}{150} = \frac{150}{150} - \frac{149}{150} = \frac{150-149}{150} = \frac{1}{150}$$ в) $$6 \frac{5}{8} = \frac{6 \cdot 8 + 5}{8} = \frac{48 + 5}{8} = \frac{53}{8}$$ г) $$12 \frac{7}{9} = \frac{12 \cdot 9 + 7}{9} = \frac{108 + 7}{9} = \frac{115}{9}$$