Question 126711
Call the smaller number {{{a}}}
and the larger number {{{b}}}
{{{b = a + 12}}}
{{{a + 2b = 39}}}
rearrange the 1st equation
{{{a - b = -12}}}
multiply both sides by {{{-1}}}
{{{-a + b = 12}}}
{{{a + 2b = 39}}}
Add these equations
{{{3b = 51}}}
{{{b = 17}}}
{{{a = 39 - 2b}}}
{{{a = 39 - 34}}}
{{{a = 5}}}
The larger number is 17
check answer
{{{b = a + 12}}}
{{{a + 2b = 39}}}
---------------
{{{17 + 5 = 12}}}
{{{5 + 34 = 39}}}
OK