Question 126022
Call the numbers {{{a}}} and {{{b}}}
{{{b = a + 12}}}
{{{a + 2b = 39}}}
---------------
{{{a - b = -12}}}
{{{a + 2b = 39}}}
Multiply the 1st equation by {{{-1}}} and add them
{{{-a + b = 12}}}
{{{a + 2b = 39}}}
----------------
{{{3b = 51}}}
{{{b = 17}}} answer