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)

a) \(\&\text{nbsp}; \frac{1}{5} + \frac{4}{5} : x = 0 , 75\)

\(\&\text{nbsp}; \frac{1}{5} + \frac{4}{5} : x = \frac{3}{4}\)

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

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

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

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) \(2 \cdot \left(\left(\right. \frac{- 3}{2} \left.\right)\right)^{2} - \frac{7}{2} = 2 \cdot \frac{9}{4} - \frac{7}{2} = \frac{9}{2} - \frac{7}{2} = 1\);
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) \(A = \left(\right. \frac{1}{3} + \frac{2}{3} \left.\right) - \left(\right. \frac{8}{15} + \frac{7}{15} \left.\right) + \left(\right. \frac{- 1}{7} + 1 \frac{1}{7} \left.\right) = 1 - 1 + 1 = 1\);
b) \(B = \left(\right. 0.25 - 1 \frac{1}{4} \left.\right) + \left(\right. \frac{3}{5} + \frac{2}{5} \left.\right) - \frac{1}{8}\)
\(= \left(\right. \frac{1}{4} - 1 - \frac{1}{4} \left.\right) + 1 - \frac{1}{8} = \frac{- 1}{8}\).