a simplified version of the problem
does 6÷2a = 3a or 3/a?
6 ÷ 2 x a is clearly 3a, but i would bet most people would say 6÷2a = 3/a.
i don't think you can both assume the x is there and deny the assumption that the 2(1+2) is a unit equivalent to (2(1+2)). as written, the problem is...