2.164 Найдите сумму: a) $${\frac{1}{6}} + {\frac{5}{8}}$$; б) $${\frac{7}{8}} + {\frac{5}{14}}$$; в) $$10{\frac{7}{25}}$$; г) $${\frac{27}{70}} + {\frac{16}{105}}$$; д) $$18{\frac{11}{81}}$$; e) $$12{\frac{5}{44}} + {\frac{3}{44}}$$; ж) $$56{\frac{15}{84}} + {\frac{11}{84}}$$; з) $$21{\frac{11}{49}} + {\frac{3}{49}}$$; 2.165 Найдите разность: a) $$6{\frac{5}{6}} - {\frac{5}{10}}$$; б) $$20{\frac{3}{28}}$$; в) $$4{\frac{3}{4}} - {\frac{1}{14}}$$; г) $$15{\frac{7}{39}} - {\frac{2}{7}}$$; д) $$33{\frac{26}{44}} - {\frac{7}{44}}$$; e) $$21{\frac{11}{14}} - {\frac{3}{14}}$$; ж) $$22{\frac{9}{26}} - {\frac{7}{26}}$$; з) $$40{\frac{33}{15}} - {\frac{7}{15}}$$

2.164 Найдите сумму:

1. a) $${\frac{1}{6}} + {\frac{5}{8}} = {\frac{4}{24}} + {\frac{15}{24}} = {\frac{19}{24}}$$
2. б) $${\frac{7}{8}} + {\frac{5}{14}} = {\frac{49}{56}} + {\frac{20}{56}} = {\frac{69}{56}} = 1{\frac{13}{56}}$$
3. в) Это просто смешанное число: $$10{\frac{7}{25}}$$
4. г) $${\frac{27}{70}} + {\frac{16}{105}} = {\frac{81}{210}} + {\frac{32}{210}} = {\frac{113}{210}}$$
5. д) Это просто смешанное число: $$18{\frac{11}{81}}$$
6. e) $$12{\frac{5}{44}} + {\frac{3}{44}} = 12{\frac{5+3}{44}} = 12{\frac{8}{44}} = 12{\frac{2}{11}}$$
7. ж) $$56{\frac{15}{84}} + {\frac{11}{84}} = 56{\frac{15+11}{84}} = 56{\frac{26}{84}} = 56{\frac{13}{42}}$$
8. з) $$21{\frac{11}{49}} + {\frac{3}{49}} = 21{\frac{11+3}{49}} = 21{\frac{14}{49}} = 21{\frac{2}{7}}$$

2.165 Найдите разность:

1. a) $$6{\frac{5}{6}} - {\frac{5}{10}} = 6{\frac{5}{6}} - {\frac{1}{2}} = 6{\frac{5}{6}} - {\frac{3}{6}} = 6{\frac{2}{6}} = 6{\frac{1}{3}}$$
2. б) Это просто смешанное число: $$20{\frac{3}{28}}$$
3. в) $$4{\frac{3}{4}} - {\frac{1}{14}} = 4{\frac{21}{28}} - {\frac{2}{28}} = 4{\frac{19}{28}}$$
4. г) $$15{\frac{7}{39}} - {\frac{2}{7}} = 15{\frac{49}{273}} - {\frac{78}{273}} = 14{\frac{49+273}{273}} - {\frac{78}{273}} = 14{\frac{322-78}{273}} = 14{\frac{244}{273}}$$
5. д) $$33{\frac{26}{44}} - {\frac{7}{44}} = 33{\frac{26-7}{44}} = 33{\frac{19}{44}}$$
6. e) $$21{\frac{11}{14}} - {\frac{3}{14}} = 21{\frac{11-3}{14}} = 21{\frac{8}{14}} = 21{\frac{4}{7}}$$
7. ж) $$22{\frac{9}{26}} - {\frac{7}{26}} = 22{\frac{9-7}{26}} = 22{\frac{2}{26}} = 22{\frac{1}{13}}$$
8. з) $$40{\frac{33}{15}} - {\frac{7}{15}} = 40{\frac{33-7}{15}} = 40{\frac{26}{15}} = 41{\frac{11}{15}}$$