Answer:
see attached
Explanation:
You want to finish filling the given 2-way table.
Totals
Any single missing value in a row or column will be the value that makes the total correct for that row or column. Filling the single missing values will fill enough of a row or column with two or more missing values so that the remaining missing values can be filled the same way.
It is basically a series of subtraction problems.
For example, the upper left cell is filled with 20 -4 = 16, so the total on that row is 16+4=20.