\(\text{Chu vi của mảnh vườn là: }\)

\(\text{(5,5 + 3,75) . 2 = 18,5 (m) }\)

\(\text{ Số khóm hoa cần trồng là: }\)

\((18,5:\dfrac{1}{4})-4=70(khómhoa)\)

\(\text{Vậy số khóm hoa cần trồng là 74}\)

a)\(\dfrac{4}{5}:x=0,75-\dfrac{1}{5}\)

\(\dfrac{4}{5}:x=\dfrac{11}{20}\)

\(x=\dfrac{11}{20}:\dfrac{4}{5}\)

\(x=\dfrac{11}{16}\)

b)\(2x=1-\dfrac{1}{2}\)

\(2x=\dfrac{1}{2}\)

\(x=\dfrac{1}{4}\)

a)\(\dfrac{2}{3}.(\dfrac{5}{4}-\dfrac{3}{4})\)

\(\dfrac{2}{3}.\dfrac{1}{2}=\dfrac{1}{3}\)

b)\(2.\dfrac{9}{4}-\dfrac{7}{2}\)

\(=\dfrac{9}{2}-\dfrac{7}{2}\)

\(=1\)

c)\(=(-\dfrac{3}{4}).\dfrac{68}{13}+(-\dfrac{3}{4}).\dfrac{36}{13}\)

\(=(-\dfrac{3}{4}).(\dfrac{68}{13}-\dfrac{36}{13})\)

\(=(-\dfrac{3}{4}).8\)

\(=(-6)\)