• № 1. Выполните действия a) 3+2; 6) 4+3; B) 810-420) 71-3.

• а) 3 \(\frac{7}{8}\) + 2 \(\frac{5}{12}\) = \(\frac{3 \cdot 24 + 7 \cdot 3 + 2 \cdot 24 + 5 \cdot 2}{24}\) = \(\frac{72 + 21 + 48 + 10}{24}\) = \(\frac{151}{24}\) = 6 \(\frac{7}{24}\)
• б) 4 \(\frac{9}{14}\) + 3 \(\frac{4}{21}\) = \(\frac{4 \cdot 42 + 9 \cdot 3 + 3 \cdot 42 + 4 \cdot 2}{42}\) = \(\frac{168 + 27 + 126 + 8}{42}\) = \(\frac{329}{42}\) = 7 \(\frac{35}{42}\) = 7 \(\frac{5}{6}\)
• в) 8 \(\frac{8}{15}\) - 4 \(\frac{9}{20}\) = \(\frac{8 \cdot 60 + 8 \cdot 4 - 4 \cdot 60 - 9 \cdot 3}{60}\) = \(\frac{480 + 32 - 240 - 27}{60}\) = \(\frac{245}{60}\) = 4 \(\frac{5}{60}\) = 4 \(\frac{1}{12}\)
• г) 7 \(\frac{1}{10}\) - 3 \(\frac{1}{6}\) = \(\frac{7 \cdot 30 + 1 \cdot 3 - 3 \cdot 30 - 1 \cdot 5}{30}\) = \(\frac{210 + 3 - 90 - 5}{30}\) = \(\frac{118}{30}\) = 3 \(\frac{28}{30}\) = 3 \(\frac{14}{15}\)

Ответ: а) 6 \(\frac{7}{24}\); б) 7 \(\frac{5}{6}\); в) 4 \(\frac{1}{12}\); г) 3 \(\frac{14}{15}\)