Let the number of comic books on each shelf originally be \( x \).
Since there are 5 shelves, the total number of comic books in the collection before the father added any is:
\[ 5x \]
According to the problem, after adding 20 comic books to the bottom shelf, this shelf now has 125 comic books. Therefore, we can set up the equation:
\[ x + 20 = 125 \]
Now, solve for \( x \):
\[ x = 125 - 20 \] \[ x = 105 \]
This means originally, each shelf had 105 comic books. To find the total number of comic books in the collection before the addition, calculate:
\[ 5x = 5 \times 105 = 525 \]
So, originally, Jose had 525 comic books. After the addition of 20 comic books to the bottom shelf, the total number of comic books in his collection becomes:
\[ 525 + 20 = 545 \]
In summary:
- Originally, each shelf had 105 comic books.
- The total collection was originally 525 comic books.
- After the father added 20 comics, the total is now 545 comic books.