Question 524711
This just an addition of 2 numbers. There is no way 
to know what {{{x}}} is, so it can be anything.
Suppose {{{ x = 2 }}}, then
{{{ 8x = 8*2 }}}
{{{ 8x = 16 }}}
and
{{{ 5x = 5*2 }}}
{{{ 5x = 10 }}}
then
{{{ 8x + 5x = 16 + 10 }}}
{{{ 8x + 5x = 26 }}}
Now suppose I add {{{ 8x + 5x = 13x }}}
{{{ 13x = 13*2 }}}
{{{ 13x = 26 }}}
I get the same answer either way.
{{{x}}} can be any real number and this still works
Hope this helps