\[ (x + 3y) + (5x - 3y) = 8 + 4 \]
\[ 6x = 12 \]
\[ x = \frac{12}{6} \]
\[ x = 2 \]
\[ 2 + 3y = 8 \]
\[ 3y = 8 - 2 \]
\[ 3y = 6 \]
\[ y = \frac{6}{3} \]
\[ y = 2 \]
\[ 5(2) - 3(2) = 10 - 6 = 4 \]
Равенство верно.
Ответ: \(x = 2, y = 2\)