Question 1142971
Let the tens digit = {{{ t }}}
Let the units digit = {{{ u }}}
{{{ t > u }}}
{{{ t + u = 12 }}}
{{{ ( 10t + u ) - ( 10u + t ) = 18 }}}
-------------------------------------
{{{ 10t + u - 10u - t = 18 }}}
{{{ 9t - 9u = 18 }}}
{{{ t - u = 2 }}}
{{{ t + u = 12 }}} ( add the equations )
--------------------
{{{ 2t = 14 }}}
{{{ t = 7 }}}
and
{{{ t + u = 12 }}}
{{{ 7 + u = 12 }}}
{{{ u = 5 }}}
--------------------
The number is 75
---------------------
check:
{{{ ( 10t + u ) - ( 10u + t ) = 18 }}}
{{{ 75 - 57 = 18 }}}
{{{ 18 = 18 }}}
OK