a) $2x + 3y = 2$;

$\Leftrightarrow 3y = 2 - 2x$

$\Leftrightarrow y = \frac{2}{3} - \frac{2x}{3}$.

Đáp số: (x; y) = ($x \in R$; $y = \frac{2}{3} - \frac{2x}{3}$)

b) $3x - 2y = 5$;

$\Leftrightarrow 2y = 3x - 5$

$\Leftrightarrow y = \frac{3x}{2} - \frac{5}{2}$.

Đáp số: (x; y) = ($x \in R$; $y = \frac{3x}{2} - \frac{5}{2}$)

c) $3x + 2y = 5$;

$\Leftrightarrow 2y = -3x + 5$

$\Leftrightarrow y = \frac{-3x}{2} + \frac{5}{2}$.

Đáp số: (x; y) = ($x \in R$; $y = \frac{-3x}{2} + \frac{5}{2}$)

d) $6x + 15y = 4$

$\Leftrightarrow 15y = -6x + 4$

$\Leftrightarrow y = \frac{-6x}{15} + \frac{4}{15}$.

Đáp số: (x; y) = ($x \in R$; $y =  \frac{-6x}{15} + \frac{4}{15}$)