Question 496655
Let {{{n}}} = the original number
{{{ 2n + 12 = (1/2)*n }}}
Multiply both sides by {{{2}}}
{{{ 4n + 24 = n }}}
Subtract {{{n}}} from both sides
{{{ 3n + 24 = 0 }}}
Subtract {{{24}}} from both sides
{{{ 3n = -24 }}}
Divide both sides by {{{3}}}
{{{ n = -8 }}}
the original number was -8
check:
double it is -16
Add 12, and you have -4
-4 is half of -8
OK