Giải thích các bước giải:
\(\begin{array}{*{20}{l}}
{a.\frac{x}{{10}} - \left( {\frac{x}{{30}} + \frac{{2x}}{{45}}} \right) = \frac{4}{5}}\\
{ \to \frac{{9x}}{{90}} - \left( {\frac{{3x}}{{90}} + \frac{{4x}}{{90}}} \right) = \frac{{4.18}}{{90}}}\\
{ \to 9x - 7x = 72}\\
{ \to 2x = 72 \to x = 36}\\
{b.\frac{{10x - 5}}{{18}} + \frac{{x + 3}}{{12}} = \frac{{7x + 3}}{6} - \frac{{12 - x}}{9}}\\
{ \to \frac{{20x - 10}}{{36}} + \frac{{3x + 9}}{{36}} = \frac{{42x + 18}}{{36}} - \frac{{48 - 4x}}{{36}}}\\
{ \to 20x - 10 + 3x + 9 = 42x + 18 - 48 + 4x}\\
{ \to - 23x = - 29}\\
{ \to x = \frac{{29}}{{23}}}\\
{c.\frac{{10x + 3}}{8} = \frac{{7 - 8x}}{{12}}}\\
{ \to 30x + 9 = 14 - 16x}\\
{ \to 46x = 5 \to x = \frac{5}{{46}}}\\
{d.\frac{{x + 4}}{5} - x - 5 = \frac{{x + 3}}{2} - \frac{{x - 2}}{2}}\\
{ \to 2x + 8 - 10x - 50 = 5x + 15 - 5x + 10}\\
{ \to {\rm{ \;}} - 8x = 67}\\
{{\rm{\;}} \to x = {\rm{ \;}}\frac{{ - 67}}{8}}
\end{array}\)
