/569

а) 3/20×3-3/10÷2

б) 1/18×7+5/6÷3

в) 5/11÷2+21/22÷3

г) 2/25×10-7/10÷2

/570

а) 4/45×9-2/3÷5

б) 3/8÷6+5/32×4

в) 5/12÷10+7/48×3

г) 7/36×4-5/9÷2

№569
a) [tex] \frac{3}{20}*3- \frac{3}{10}:2= \frac{3*3}{20}- \frac{3}{10}* \frac{1}{2}= \frac{9}{20}- \frac{3}{20}= \frac{9-3}{20}= \frac{6}{20}= \frac{3}{10} [/tex]
б) [tex] \frac{1}{18}*7+ \frac{5}{6}:3= \frac{7}{18}+ \frac{5}{6}* \frac{1}{3}= \frac{7}{18}+ \frac{5}{18}= \frac{7+5}{18}= \frac{12}{18}= \frac{2}{3} [/tex]
в) [tex] \frac{5}{11}:2+ \frac{21}{22}:3= \frac{5}{11}* \frac{1}{2}+ \frac{21}{22}* \frac{1}{3}= \frac{5}{22}+ \frac{21}{66}= \frac{5*3+21}{66}= \frac{36}{66}= \frac{6}{11} [/tex]
г) [tex] \frac{2}{25}*10- \frac{7}{10}:2= \frac{2*10}{25}- \frac{7}{10} * \frac{1}{2}= \frac{20}{25}- \frac{7}{20}= \frac{20*4-7*5}{100}= \frac{80-35}{100}= \frac{45}{100} [/tex][tex]= \frac{9}{20}[/tex]

№570
а) [tex] \frac{4}{45}*9 - \frac{2}{3}:5 = \frac{4*9}{45}- \frac{2}{3}* \frac{1}{5}= \frac{36}{45}- \frac{2}{15}= \frac{36-2*3}{45}= \frac{30}{45}= \frac{2}{3} [/tex]
б) [tex] \frac{3}{8}:6+ \frac{5}{32}*4= \frac{3}{8} * \frac{1}{6} + \frac{5*4}{32}= \frac{3}{48} + \frac{20}{32}= \frac{3*2+20*3}{96}= \frac{66}{96}= \frac{11}{16} [/tex]
в) [tex] \frac{5}{12} :10+ \frac{7}{48}*3= \frac{5}{12} * \frac{1}{10} + \frac{7*3}{48}= \frac{5}{120} + \frac{21}{48}= \frac{1}{24}+ \frac{21}{48}= \frac{1*2+21}{48}= \frac{23}{48} [/tex]
г) [tex] \frac{7}{36} *4- \frac{5}{9} :2= \frac{7*4}{36} - \frac{5}{9} * \frac{1}{2}= \frac{28}{36} - \frac{5}{18} = \frac{28-5*2}{36}= \frac{18}{36}= \frac{1}{2} [/tex]