To find the value of \( x \) where the two lines \( y = 2x + 3 \) and \( y = x - 7 \) intersect, we can set the equations equal to each other since both equations represent \( y \).
So we set:
\[ 2x + 3 = x - 7 \]
Now, we will solve for \( x \):
- Subtract \( x \) from both sides:
\[ 2x - x + 3 = -7 \]
This simplifies to:
\[ x + 3 = -7 \]
- Next, subtract \( 3 \) from both sides:
\[ x = -7 - 3 \]
This simplifies to:
\[ x = -10 \]
So the value of \( x \) at which the two lines intersect is:
\[ \boxed{-10} \]