Вычислим значения выражений:

a)

$$\frac{1}{2} + \frac{3}{4} + \frac{5}{8} = \frac{4}{8} + \frac{6}{8} + \frac{5}{8} = \frac{4+6+5}{8} = \frac{15}{8} = 1\frac{7}{8}$$

б)

$$\frac{23}{24} - \frac{5}{12} - \frac{1}{6} = \frac{23}{24} - \frac{10}{24} - \frac{4}{24} = \frac{23-10-4}{24} = \frac{9}{24} = \frac{3}{8}$$

в)

$$\frac{5}{8} + \frac{1}{3} + \frac{7}{12} = \frac{15}{24} + \frac{8}{24} + \frac{14}{24} = \frac{15+8+14}{24} = \frac{37}{24} = 1\frac{13}{24}$$

г)

$$\frac{5}{6} - \frac{1}{8} + \frac{5}{12} = \frac{20}{24} - \frac{3}{24} + \frac{10}{24} = \frac{20-3+10}{24} = \frac{27}{24} = \frac{9}{8} = 1\frac{1}{8}$$

д)

$$3\frac{5}{7} + 4\frac{9}{14} - 2\frac{5}{21} = 3\frac{30}{42} + 4\frac{27}{42} - 2\frac{10}{42} = (3+4-2) + (\frac{30}{42} + \frac{27}{42} - \frac{10}{42}) = 5 + \frac{30+27-10}{42} = 5 + \frac{47}{42} = 5 + 1\frac{5}{42} = 6\frac{5}{42}$$

е)

$$2\frac{1}{3} + \frac{1}{5} - 1\frac{1}{8} = \frac{7}{3} + \frac{1}{5} - \frac{9}{8} = \frac{280}{120} + \frac{24}{120} - \frac{135}{120} = \frac{280+24-135}{120} = \frac{169}{120} = 1\frac{49}{120}$$

Ответ:

• a) $$1\frac{7}{8}$$
• б) $$\frac{3}{8}$$
• в) $$1\frac{13}{24}$$
• г) $$1\frac{1}{8}$$
• д) $$6\frac{5}{42}$$
• е) $$1\frac{49}{120}$$