Question

решите пожалуйста 5 класс

Answer 1

1)
$( frac{5}{21} + frac{2}{15} )+ frac{2}{21} = frac{5}{21} + frac{2}{21} + frac{2}{15} = frac{7}{21} + frac{2}{15} = frac{1}{3} + frac{2}{15} = frac{5+2}{15} = frac{7}{15}$
2)
$( frac{2}{35} + frac{3}{28} )+ frac{1}{28} = frac{3}{28} + frac{1}{28} + frac{2}{35} = frac{4}{28} + frac{2}{35} = frac{1}{7} + frac{2}{35} = frac{5+2}{35} = frac{7}{35} = frac{1}{5}$
3)
$( frac{7}{30} + frac{8}{45} )+( frac{2}{45} + frac{1}{30} )=( frac{7}{30} + frac{1}{30} )+ (frac{8}{45} + frac{2}{45} )= frac{8}{30} + frac{10}{45} = frac{4}{15} + frac{2}{9} =$$frac{12+10}{45} = frac{22}{45}$
4)
$( frac{5}{24} + frac{11}{60} )+ ( frac{13}{60} + frac{1}{24} )=( frac{5}{24} + frac{1}{24} )+( frac{11}{60} + frac{13}{60} )= frac{6}{24} + frac{24}{60} = frac{1}{4} + frac{2}{5} = frac{5+8}{20}$$= frac{13}{20}$