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5) $2 \frac{1}{52}* \frac{26}{49}-1 \frac{11}{21}:2 \frac{2}{9}= \frac{105}{52}* \frac{26}{49}- \frac{32}{21}: \frac{20}{9} = \frac{7*15*26}{2*26*7*7}- \frac{4*8}{3*7}* \frac{3*3}{4*5}=$
$= \frac{15}{2*7}- \frac{8}{7}* \frac{3}{5}= \frac{15}{14}- \frac{24}{35}= \frac{15*5}{14*5}- \frac{24*2}{35*2} = \frac{75}{70} - \frac{48}{70} = \frac{27}{70}$
5) $8 \frac{3}{4}*2 \frac{4}{7}-10 \frac{1}{8}*3 \frac{1}{3}= \frac{35}{4}* \frac{32}{7}- \frac{81}{8}* \frac{10}{3}= \frac{5*7*4*8}{4*7}- \frac{3*27*2*5}{2*4*3}=$
$= 5*8- \frac{27*5}{4}=40- \frac{135}{4}= \frac{160-135}{4} = \frac{25}{4}$
5) $-3 \frac{5}{21}:1 \frac{22}{63}+1 \frac{3}{35}:1 \frac{1}{56} =- \frac{68}{21}: \frac{85}{63} + \frac{38}{35}: \frac{57}{56} =- \frac{68}{21 }* \frac{63}{85}+ \frac{38}{35}* \frac{56}{57} =$
$=- \frac{17*4}{21 }* \frac{21*3}{17*5}+ \frac{2*19}{5*7}* \frac{8*7}{3*19} = - \frac{4*3}{5} + \frac{2*8}{5*3} =- \frac{12}{5}+ \frac{16}{15} = \frac{-36+16}{15} =- \frac{4}{3}$