Mathematics · Matrix Number Puzzle

In the following matrix, the values of variables A, B, C, and D are constant across all rows and columns. The total sum of each row and column is given (except for one missing row total). Find the missing row total represented by '?'. Row 1: A, B, B, C | Total = 30 Row 2: B, A, B, C | Total = 30 Row 3: B, D, D, D | Total = 30 Row 4: C, A, D, C | Total = ? Column Totals (1 to 4): 30, 30, 32, 37