a) \(\frac{5}{6}+\frac{7}{12}-\frac{2}{3}\)=\(\frac{10}{12}+\frac{7}{12}-\frac{8}{12}\)=\(\frac{9}{12}=\frac{3}{4}\)
b) \(\frac{3}{4}-1\frac{1}{2}+50\%:\frac{5}{12}\)=\(\frac{3}{4}-\frac{3}{2}+\frac{1}{2}:\frac{5}{12}\)=\(\frac{3}{4}-\frac{3}{2}+\frac{6}{5}\)=\(\frac{30}{40}-\frac{60}{40}+\frac{48}{40}\)= \(\frac{18}{40}\)=\(\frac{9}{20}\)
c)ghi lại đề hộ mk, mk ko rõ
c) \(\frac{2}{7}.5\frac{1}{4}-\frac{2}{7}.3\frac{1}{4}\)=\(\frac{2}{7}.\frac{21}{4}-\frac{2}{7}.\frac{13}{4}\)=\(\frac{3}{2}\)-\(\frac{13}{14}\)=\(\frac{21}{14}-\frac{13}{14}\)=\(\frac{8}{14}=\frac{4}{7}\)