Question 155498
{{{abs(x + a) = b}}}
So
{{{x + a = b }}} and {{{x + a = -b}}}
Thus, the two solutions are
{{{x = b-a}}} and {{{x = -b-a}}}

In order to have the two solutions be the same,
{{{b - a = -b - a}}}
{{{b = -b}}}
Only b = 0 satisfies this.
x = -a, b = 0