270. Найдите значение выражения, предварительно сократив дроби: 1) 25/80 + 45/60; 2) 20/45 + 26/54; 3) 36/300 + 12/40 − 350/1000; 4) 14/24 − 39/90 + 15/100; 5) 42/120 + 20/32 − 28/160; 6) 45/72 − 33/144 − 20/64.

Question

Вопрос:

Accepted Answer

\(\frac{25}{80}+\frac{45}{60}=\frac{5}{16}+\frac{3}{4}=\frac{5}{16}+\frac{12}{16}=\frac{17}{16}\).
\(\frac{20}{45}+\frac{26}{54}=\frac{4}{9}+\frac{13}{27}=\frac{12}{27}+\frac{13}{27}=\frac{25}{27}\).
\(\frac{36}{300}+\frac{12}{40}-\frac{350}{1000}=\frac{3}{25}+\frac{3}{10}-\frac{7}{20}=\frac{12}{100}+\frac{30}{100}-\frac{35}{100}=\frac{7}{100}\).
\(\frac{14}{24}-\frac{39}{90}+\frac{15}{100}=\frac{7}{12}-\frac{13}{30}+\frac{3}{20}=\frac{35}{60}-\frac{26}{60}+\frac{9}{60}=\frac{18}{60}=\frac{3}{10}\).
\(\frac{42}{120}+\frac{20}{32}-\frac{28}{160}=\frac{7}{20}+\frac{5}{8}-\frac{7}{40}=\frac{14}{40}+\frac{25}{40}-\frac{7}{40}=\frac{32}{40}=\frac{4}{5}\).
\(\frac{45}{72}-\frac{33}{144}-\frac{20}{64}=\frac{5}{8}-\frac{11}{48}-\frac{5}{16}=\frac{30}{48}-\frac{11}{48}-\frac{15}{48}=\frac{4}{48}=\frac{1}{12}\).

Ответ: 1) \(\frac{17}{16}\); 2) \(\frac{25}{27}\); 3) \(\frac{7}{100}\); 4) \(\frac{3}{10}\); 5) \(\frac{4}{5}\); 6) \(\frac{1}{12}\).