chieu dai ta trong dc la :\(5.5\div\dfrac{1}{4}=22(khamhao)\)

chieu rong ta trong hoa dc la:\(3.75\div\dfrac{1}{4}=15(khomhoa)\)

khom hoa trong dc la:\(([22+15)\times2]-4=70(khomhoa)\)

\(a,\dfrac{1}{5}+\dfrac{4}{5}\div\chi=\dfrac{3}{4}\)\(\dfrac{4}{5}\div\chi=\dfrac{3}{4}-\dfrac{1}{5}\)\(\dfrac{4}{5}\div\chi=\dfrac{11}{20}\)\(\chi=\dfrac{4}{5}\div\dfrac{11}{20}\)\(\chi=\dfrac{6}{11}\)\(b,2\chi=1-\dfrac{1}{2}\)\(2\chi=\dfrac{1}{2}\)\(\chi=\dfrac{1}{4}\)

\(a,\dfrac{2}{3}\times\left(\dfrac{5}{4}-\dfrac{3}{4}\right)=\dfrac{2}{3}\times\dfrac{1}{2}=\dfrac{1}{3}\)\(c,\dfrac{-3}{4}\times5^3_{13}-0.75\times\dfrac{36}{13}=\dfrac{-3}{4}\times(5^3_{13}+\dfrac{36}{13})=-6\)\(b,2\times\dfrac{9}{4}-\dfrac{7}{2}=\dfrac{9}{2}-\dfrac{7}{2}=1\)