a)81-\frac{4}{5} б)7-6\frac{2}{7} в)5\frac{1}{3}+3\frac{1}{3} 2)7+3\frac{5}{4} д)5\frac{2}{5}+6\frac{3}{5} е)3+2\frac{1}{2}

a) $$\begin{array}{rcl}8 \frac{1}{5} - \frac{4}{5} &=& 7 \frac{6}{5} - \frac{4}{5} = 7 \frac{6-4}{5} = 7 \frac{2}{5}\end{array}$$

Ответ: $$7 \frac{2}{5}$$

б) $$7-6\frac{2}{7} = 6\frac{7}{7}-6\frac{2}{7} = \frac{6-6}{7} + \frac{7-2}{7} = \frac{5}{7}$$

Ответ: $$\frac{5}{7}$$

в) $$5\frac{1}{3}+3\frac{1}{3} = (5+3) + (\frac{1}{3}+\frac{1}{3}) = 8 + \frac{1+1}{3} = 8 + \frac{2}{3} = 8\frac{2}{3}$$

Ответ: $$8\frac{2}{3}$$

г) $$7+3\frac{5}{4} = 7+3+\frac{5}{4} = 10 + \frac{5}{4} = 10 + 1\frac{1}{4} = 11\frac{1}{4}$$

Ответ: $$11\frac{1}{4}$$

д) $$5\frac{2}{5}+6\frac{3}{5} = (5+6) + (\frac{2}{5}+\frac{3}{5}) = 11 + \frac{2+3}{5} = 11 + \frac{5}{5} = 11 + 1 = 12$$

Ответ: $$12$$

e) $$3+2\frac{1}{2} = 3+2+\frac{1}{2} = 5 + \frac{1}{2} = 5\frac{1}{2}$$

Ответ: $$5\frac{1}{2}$$