Dọc theo chiều dài, ta trồng được:

\(5.5 : \frac{1}{4} = 22\) (khóm hoa)

Dọc theo chiều rộng, ta trồng được:

\(3 , 75 : \frac{1}{4} = 15\) (khóm hoa)

Như vậy, số khóm hoa trồng được dọc theo hai cạnh của mảnh vườn là:

\(\left[\right. \left(\right. 22 + 15 \left.\right) . 2 \left]\right. - 4 = 70\) (khóm hoa)

Vậy ta trồng được 70 khóm hoa

 \(\frac{1}{5}+\frac{4}{5}:x=0,75\)

\(\frac{1}{5}+\frac{4}{5}:x=\frac{3}{4}\)

\(\frac{4}{5} : x = \frac{3}{4} - \frac{1}{5}\)

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

\(x = \frac{16}{11}\);

b) \(x + \frac{1}{2} = 1 - x\)

 \(2 x = 1 - \frac{1}{2}\)

 \(2 x = \frac{1}{2}\)

 \(x = \frac{1}{4}\).

a) \(\frac{2}{3} \cdot \frac{5}{4} - \frac{3}{4} \cdot \frac{2}{3} = \frac{2}{3} \cdot \left(\right. \frac{5}{4} - \frac{3}{4} \left.\right) = \frac{2}{3} \cdot \frac{1}{2} = \frac{1}{3}\)

b) \(2\cdot\left(\right.\frac{- 3}{2}\left.\right)^2-\frac{7}{2}=2\cdot\frac{9}{4}-\frac{7}{2}=\frac{9}{2}-\frac{7}{2}=1\)

c) \(- \frac{3}{4} \cdot 5 \frac{3}{13} - 0 , 75 \cdot \frac{36}{13} = - \frac{3}{4} \cdot 5 \frac{3}{13} - \frac{3}{4} \cdot \frac{36}{13}\)
\(= - \frac{3}{4} \left(\right. 5 \frac{3}{13} + \frac{36}{13} \left.\right)\)
\(= - \frac{3}{4} \cdot 8 = - 6\)

a) \(\frac{2}{3} \cdot \frac{5}{4} - \frac{3}{4} \cdot \frac{2}{3} = \frac{2}{3} \cdot \left(\right. \frac{5}{4} - \frac{3}{4} \left.\right) = \frac{2}{3} \cdot \frac{1}{2} = \frac{1}{3}\)

b) \(2\cdot\left(\right.\frac{- 3}{2}\left.\right)^2-\frac{7}{2}=2\cdot\frac{9}{4}-\frac{7}{2}=\frac{9}{2}-\frac{7}{2}=1\)

c) \(- \frac{3}{4} \cdot 5 \frac{3}{13} - 0 , 75 \cdot \frac{36}{13} = - \frac{3}{4} \cdot 5 \frac{3}{13} - \frac{3}{4} \cdot \frac{36}{13}\)
\(= - \frac{3}{4} \left(\right. 5 \frac{3}{13} + \frac{36}{13} \left.\right)\)
\(= - \frac{3}{4} \cdot 8 = - 6\)

a) \(\frac{2}{3} \cdot \frac{5}{4} - \frac{3}{4} \cdot \frac{2}{3} = \frac{2}{3} \cdot \left(\right. \frac{5}{4} - \frac{3}{4} \left.\right) = \frac{2}{3} \cdot \frac{1}{2} = \frac{1}{3}\)

b) \(2\cdot\left(\right.\frac{- 3}{2}\left.\right)^2-\frac{7}{2}=2\cdot\frac{9}{4}-\frac{7}{2}=\frac{9}{2}-\frac{7}{2}=1\)

c) \(- \frac{3}{4} \cdot 5 \frac{3}{13} - 0 , 75 \cdot \frac{36}{13} = - \frac{3}{4} \cdot 5 \frac{3}{13} - \frac{3}{4} \cdot \frac{36}{13}\)
\(= - \frac{3}{4} \left(\right. 5 \frac{3}{13} + \frac{36}{13} \left.\right)\)
\(= - \frac{3}{4} \cdot 8 = - 6\)