To solve the equation \( 7x - 5 = 3x + 15 \), follow these steps:
- Subtract \( 3x \) from both sides:
\[ 7x - 3x - 5 = 15 \]
This simplifies to:
\[ 4x - 5 = 15 \]
- Next, add \( 5 \) to both sides:
\[ 4x - 5 + 5 = 15 + 5 \]
This simplifies to:
\[ 4x = 20 \]
- Now, divide both sides by \( 4 \):
\[ x = \frac{20}{4} \]
This gives:
\[ x = 5 \]
So the solution is:
\[ \boxed{5} \]