Problem: 80 white and black tiles will be used to form a 10 x 10 square pattern . if there must be at least one black tile in every row and at least one white tile in every column , what is the maximum difference between the number of black and white tiles that can be used ?
Rationale: "answer = e please refer diagram below 70 - 10 = 60"
annotated_formula: subtract(80, 10)