Table:
lowest quartile
second quartile
third quartile
highest quartile
total

percent

mobile devices only
24.1
14.7
13.8
8.0
13.5

personal computer
75.9
85.3
86.2
92.0
86.5

This image shows a table. Tell me the row number and column number of this table. Return the result as JSON in the format {"row_number": "m", "column_number": "n"}, e.g., {"row_number": "12", "column_number": "7"}.

There are 4 rows and 6 columns in the table. So, the final answer is {"row_number": "4", "column_number": "6"}.