2.168 Найдите сумму:

1. a) $$rac{1}{6} + rac{5}{8} = rac{4}{24} + rac{15}{24} = rac{19}{24}$$
2. б) $$rac{7}{8} + rac{5}{14} = rac{49}{56} + rac{20}{56} = rac{69}{56}$$
3. в) $$rac{7}{10} + rac{3}{25} = rac{35}{50} + rac{6}{50} = rac{41}{50}$$
4. г) $$rac{27}{70} + rac{16}{105} = rac{81}{210} + rac{32}{210} = rac{113}{210}$$
5. д) $$rac{11}{18} + rac{1}{81} = rac{99}{162} + rac{2}{162} = rac{101}{162}$$
6. е) $$rac{5}{12} + rac{3}{44} = rac{55}{132} + rac{9}{132} = rac{64}{132} = rac{16}{33}$$
7. ж) $$rac{15}{56} + rac{11}{84} = rac{45}{168} + rac{22}{168} = rac{67}{168}$$
8. з) $$rac{11}{21} + rac{3}{49} = rac{77}{147} + rac{9}{147} = rac{86}{147}$$

2.169 Найдите разность:

1. a) $$rac{5}{6} - rac{5}{10} = rac{25}{30} - rac{15}{30} = rac{10}{30} = rac{1}{3}$$
2. б) $$rac{3}{20} - rac{3}{28} = rac{21}{140} - rac{15}{140} = rac{6}{140} = rac{3}{70}$$
3. в) $$rac{3}{4} - rac{1}{14} = rac{21}{28} - rac{2}{28} = rac{19}{28}$$
4. г) $$rac{7}{15} - rac{2}{39} = rac{91}{195} - rac{10}{195} = rac{81}{195} = rac{27}{65}$$
5. д) $$rac{26}{33} - rac{7}{44} = rac{104}{132} - rac{21}{132} = rac{83}{132}$$
6. е) $$rac{11}{21} - rac{3}{14} = rac{22}{42} - rac{9}{42} = rac{13}{42}$$
7. ж) $$rac{9}{22} - rac{7}{26} = rac{117}{286} - rac{77}{286} = rac{40}{286} = rac{20}{143}$$
8. з) $$rac{33}{40} - rac{7}{15} = rac{99}{120} - rac{56}{120} = rac{43}{120}$$