Question 529724
{{{ -8+3x-4x=-9 }}}
Add {{{ 8 }}} to both sides
{{{ -8 + 8 + 3x - 4x = -9 + 8 }}}
{{{ 3x - 4x = -1 }}}
On the left side, {{{ 3x - 4x = -x }}}, so
{{{ -x = -1 }}}
Multiply both sides by {{{-1}}}
{{{ (-1)*(-x) = (-1)*(-1) }}}
A minus times a minus is plus, so
{{{ x = 1 }}}
-----------
You can check this by putting {{{ x = 1 }}}
back into the original equation
{{{ -8+3x-4x=-9 }}}
{{{ -8+3*1-4*1=-9 }}}
{{{ -8 + 3 - 4 = -9 }}}
{{{ -12 + 3 = -9 }}}
{{{ -9 = -9 }}}
OK