If 5 # 3 = 7 and 7 # 2 = 5, what is 9 # 1?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. -1.
5 # 3 = 7 → (5 × 3) - (5 + 3) = 15 - 8 = 7
7 # 2 = 5 → (7 × 2) - (7 + 2) = 14 - 9 = 5
Similarly, 9 # 1? → (9 × 1) - (9 + 1) = 9 - 10 = -1