Вычислите 1)4/15+3/4 2) 5/6-9/14 3)4 4/7+6 1/4 4) 5 7/8-3 5/6

Ну вот все очень просто
1) $\frac{4}{15} + \frac{3}{4}= \frac{4*4}{15*4}+ \frac{15*3}{15*4}= \frac{16}{60}+ \frac{45}{60} = \frac{16+45}{60} = \frac{61}{60} =1 \frac{1}{60}$
2)5\6-9\14= $\frac{7*5}{7*6}$ - $\frac{3*9}{3*14}$ = $\frac{35}{42} - \frac{27}{42}$ = $\frac{35-27}{42} = \frac{8}{42}$ = $\frac{4*2}{21*2} = \frac{4}{21}$
3) $4 \frac{4}{7} + 6\frac{1}{4}$ = $\frac{4*7+4}{7} + \frac{6*4+1}{4}$ = $\frac{32}{7} + \frac{25}{4} = \frac{4*32}{7*4}$ + $\frac{7*25}{7*4}$ = $\frac{128}{28} + \frac{175}{28}$ = $\frac{128+175}{28} = \frac{303}{28}=$ $10\frac{23}{28}$
4)5 7\8-3 5\6= $\frac{5*8+7}{8} - \frac{3*6+5}{6}$ = $\frac{47}{8} - \frac{23}{6} = \frac{3*47}{3*8} - \frac{4*23}{4*6} = \frac{141}{24} - \frac{92}{24}$ = $\frac{141-92}{24}$ = $\frac{49}{24} = 2\frac{1}{24}$