To solve the equation \( 23.86 = y - 16.2 \), we can isolate \( y \) by adding \( 16.2 \) to both sides of the equation:
\[ y = 23.86 + 16.2 \]
Now, let's perform the addition:
\[ y = 23.86 + 16.2 = 40.06 \]
Therefore, the solution is:
\[ \boxed{y = 40.06} \]