Домашняя работа на все действия 1). 7/15 : (6/10 - 8/3) + 19 * 2/31

1). $\frac{7}{15}:\left(\frac{6}{10}-\frac{8}{3}\right)+19\cdot\frac{2}{31}=\frac{7}{15}:\left(\frac{18-80}{30}\right)+\frac{38}{31}=\frac{7}{15}:\left(-\frac{62}{30}\right)+\frac{38}{31}=\frac{7}{15}\cdot\left(-\frac{30}{62}\right)+\frac{38}{31}=-\frac{7}{31}+\frac{38}{31}=\frac{31}{31}=1$ 2). $\left(1\frac{1}{35}:\frac{4}{5}-1\frac{8}{35}\right)\cdot3\frac{1}{3}=\left(\frac{36}{35}\cdot\frac{5}{4}-\frac{43}{35}\right)\cdot\frac{10}{3}=\left(\frac{9}{7}-\frac{43}{35}\right)\cdot\frac{10}{3}=\left(\frac{45-43}{35}\right)\cdot\frac{10}{3}=\frac{2}{35}\cdot\frac{10}{3}=\frac{2\cdot2}{7\cdot3}=\frac{4}{21}$ 3). $2\frac{7}{9}\cdot\frac{18}{25}+\frac{9}{60}:\left(\frac{7}{12}-\frac{3}{5}\right)=\frac{25}{9}\cdot\frac{18}{25}+\frac{3}{20}:\left(\frac{35-36}{60}\right)=2+\frac{3}{20}:\left(-\frac{1}{60}\right)=2+\frac{3}{20}\cdot(-60)=2-9=-7$ 4). $\left(\frac{4}{5}+\frac{4}{7}\right)\left(3\frac{3}{8}+2\frac{11}{4}\right)=\left(\frac{28+20}{35}\right)\left(\frac{27}{8}+\frac{19}{4}\right)=\frac{48}{35}\cdot\left(\frac{27+38}{8}\right)=\frac{48}{35}\cdot\frac{65}{8}=\frac{6\cdot13}{7\cdot1}=\frac{78}{7}=11\frac{1}{7}$ 5). $-3\frac{1}{7}\cdot(-8)-2,9:0,1+\frac{11}{21}:\left(-3\frac{2}{3}\right)=\frac{22}{7}\cdot8-29+\frac{11}{21}:\left(-\frac{11}{3}\right)=\frac{176}{7}-29+\frac{11}{21}\cdot\left(-\frac{3}{11}\right)=25\frac{1}{7}-29-\frac{1}{7}=-4\frac{1}{7}$