How do you simplify (abs(1-y)) = 9e^[(-1/2)(x^2)]?

The answer is y = 1 + 9e^[(-1/2)(x^2)] but for some reason I keep getting y= 1 - 9e^[(-1/2)(x^2)].

I know it has something to with the absolute value sign so I know I'm missing something here. I'd appreciate any help regarding operations with the absolute value sign, such as how to dissolve it properly or something like that. I'm sure I've learned it somewhere a while ago but I'm sure I forgot it or something and I need a refresh.

Thanks in advance.