làm hết hay làm mấy cái bạn đánh dấu vậy ????
\(\dfrac{13}{12}-\dfrac{5}{12}=\dfrac{13-5}{12}=\dfrac{8}{12}=\dfrac{2}{3}\)
\(\dfrac{-3}{5}-\dfrac{1}{2}=\dfrac{-6}{10}-\dfrac{5}{10}=\dfrac{-11}{10}\)
\(\dfrac{-7}{3}+\dfrac{-5}{6}=\dfrac{-42}{18}-\dfrac{15}{18}=\dfrac{-57}{18}=\dfrac{-19}{6}\)
\(\dfrac{15}{4}-\dfrac{7}{2}=\dfrac{15}{4}-\dfrac{28}{4}=\dfrac{-13}{4}\)
\(\dfrac{8}{15}-\dfrac{7}{20}=\dfrac{32}{60}-\dfrac{21}{60}=\dfrac{11}{60}\)
\(\dfrac{-1}{9}+\dfrac{5}{18}=\dfrac{-2}{18}+\dfrac{5}{18}=\dfrac{3}{18}=\dfrac{1}{6}\)
\(\dfrac{-4}{7}-\dfrac{5}{10}=\dfrac{-40}{70}-\dfrac{35}{70}=\dfrac{-75}{70}=\dfrac{-15}{14}\)
10. \(\dfrac{8}{12}\)
13.\(\dfrac{-11}{10}\)
19.\(\dfrac{1}{4}\)
22.\(\dfrac{4}{60}\)=\(\dfrac{1}{5}\)
25.\(\dfrac{3}{18}=\dfrac{1}{6}\)
28.\(\dfrac{1400}{70}=20\)
10. \(\dfrac{13}{12}-\dfrac{5}{12}=\dfrac{8}{12}=\dfrac{2}{3}\)
11. \(\dfrac{5}{3}-\dfrac{-7}{2}=\dfrac{10}{6}-\dfrac{-21}{6}=\dfrac{31}{6}\)
12. \(\dfrac{-3}{4}+\dfrac{-5}{4}=\dfrac{-8}{4}=-2\)
13. \(\dfrac{3}{-5}-\dfrac{1}{2}=\dfrac{-3}{5}-\dfrac{1}{2}=\dfrac{-6}{10}-\dfrac{5}{10}=\dfrac{-11}{10}\)
14. \(\dfrac{-5}{7}+\dfrac{4}{3}=\dfrac{-15}{21}+\dfrac{28}{21}=\dfrac{13}{21}\)
15. \(\dfrac{1}{5}-\dfrac{3}{4}=\dfrac{4}{20}-\dfrac{15}{20}=\dfrac{-11}{20}\)
16. \(\dfrac{-7}{3}+\dfrac{-5}{6}=\dfrac{-14}{6}+\dfrac{-5}{6}=\dfrac{-19}{6}\)
17. \(\dfrac{7}{2}-\dfrac{9}{4}=\dfrac{14}{4}-\dfrac{9}{4}=\dfrac{5}{4}\)
18. \(\dfrac{-6}{5}-\dfrac{3}{8}=\dfrac{-48}{40}-\dfrac{15}{40}=\dfrac{-63}{40}\)
19. \(\dfrac{15}{4}-\dfrac{7}{2}=\dfrac{15}{4}-\dfrac{14}{4}=\dfrac{1}{4}\)
20. \(\dfrac{5}{3}-\dfrac{4}{-21}=\dfrac{5}{3}-\dfrac{-4}{21}=\dfrac{35}{21}-\dfrac{-4}{21}=\dfrac{39}{21}=\dfrac{13}{7}\)
21. \(\dfrac{-3}{5}-\dfrac{7}{10}=\dfrac{-6}{10}-\dfrac{7}{10}=\dfrac{-13}{10}\)
22. \(\dfrac{8}{15}+\dfrac{-7}{20}=\dfrac{160}{300}+\dfrac{-105}{300}=\dfrac{55}{300}=\dfrac{11}{60}\)
23. \(\dfrac{5}{8}-\dfrac{7}{10}=\dfrac{50}{80}-\dfrac{56}{80}=\dfrac{-6}{80}=\dfrac{-3}{40}\)
24. \(\dfrac{3}{15}-\dfrac{4}{20}=\dfrac{60}{300}-\dfrac{60}{300}=0\)
25. \(\dfrac{-1}{9}+\dfrac{5}{18}=\dfrac{-2}{18}+\dfrac{45}{18}=\dfrac{43}{18}\)
26. \(\dfrac{3}{4}-\dfrac{5}{12}=\dfrac{9}{12}-\dfrac{5}{12}=\dfrac{4}{12}=\dfrac{1}{3}\)
27. \(\dfrac{3}{5}+\dfrac{-7}{4}=\dfrac{12}{20}+\dfrac{-35}{20}=\dfrac{-23}{20}\)
28. \(\dfrac{-4}{7}+\dfrac{-5}{10}=\dfrac{-40}{70}+\dfrac{-35}{70}=\dfrac{-75}{70}=\dfrac{-15}{14}\)
29. \(\dfrac{-7}{15}-\dfrac{4}{25}=\dfrac{-175}{375}-\dfrac{60}{375}=\dfrac{-235}{375}=\dfrac{-47}{75}\)
30. \(\dfrac{-5}{8}-\dfrac{7}{18}=\dfrac{-35}{144}-\dfrac{56}{144}=\dfrac{-91}{144}\)