What seemed like a regular grade school math problem had people totally stumped on social media. The equation 9 x 3 - 9 shared by @BholanathDutta on X left social media users completely mystified.

John A. Van de Walle, Helen Holbrook, Patterns, Thinking, and Problem Solving, The Arithmetic Teacher, Vol. 34, No. 8 (April 1987), pp. 6-12 ...