Đáp án:
$\begin{array}{l}
a)\frac{2}{7} + x = - 0,75\\
\Rightarrow x = - 0,75 - \frac{2}{7}\\
\Rightarrow x = - \frac{3}{4} - \frac{2}{7}\\
\Rightarrow x = \frac{{ - 3.7 - 2.4}}{{28}} = \frac{{ - 29}}{{28}}\\
b) - 4\frac{1}{5} - x = 2,25\\
\Rightarrow - \frac{{21}}{5} - x = \frac{9}{4}\\
\Rightarrow x = - \frac{{21}}{5} - \frac{9}{4}\\
\Rightarrow x = \frac{{ - 84 - 45}}{{20}}\\
\Rightarrow x = \frac{{ - 129}}{{20}}\\
c)\frac{3}{8} - \frac{1}{6}.x = \frac{1}{4}\\
\Rightarrow \frac{1}{6}.x = \frac{3}{8} - \frac{1}{4} = \frac{1}{8}\\
\Rightarrow x = \frac{1}{8}:\frac{1}{6} = \frac{3}{4}\\
d)\left( {x - 7\frac{1}{3}} \right):2\frac{1}{4} = - 1,5\\
\Rightarrow \left( {x - \frac{{22}}{3}} \right):\frac{9}{4} = \frac{{ - 3}}{2}\\
\Rightarrow \left( {x - \frac{{22}}{3}} \right) = - \frac{3}{2}.\frac{9}{4} = \frac{{ - 27}}{8}\\
\Rightarrow x = - \frac{{27}}{8} + \frac{{22}}{3}\\
\Rightarrow x = \frac{{95}}{{24}}\\
e)\frac{x}{{15}} = \frac{3}{5} - \frac{2}{3}\\
\Rightarrow \frac{x}{{15}} = \frac{{9 - 10}}{{15}} = \frac{{ - 1}}{{15}}\\
\Rightarrow x = - 1\\
f)\frac{{x + 1}}{5} = \frac{7}{2}\\
\Rightarrow x + 1 = \frac{7}{2}.5 = \frac{{35}}{2}\\
\Rightarrow x = \frac{{35}}{2} - 1 = \frac{{33}}{2}
\end{array}$
