To find the value of \( y \) in the given system of equations, we need to solve the equations simultaneously. The equations are:
- \( y = 3x - 5 \)
- \( 6x + 3y = 15 \)
We can substitute the expression for \( y \) from the first equation into the second equation.
Substituting \( y \) in the second equation:
\[ 6x + 3(3x - 5) = 15 \]
Now, simplify the equation:
\[ 6x + 9x - 15 = 15 \]
Combine like terms:
\[ 15x - 15 = 15 \]
Add 15 to both sides:
\[ 15x = 30 \]
Now, divide by 15:
\[ x = 2 \]
Now that we have \( x \), we can substitute it back into the first equation to find \( y \):
\[ y = 3(2) - 5 \] \[ y = 6 - 5 \] \[ y = 1 \]
Thus, the value of \( y \) is \( \boxed{1} \).