Question 933046
SOLUTION: {{{highlight(1349)}}}
 
EXPLANATION:
Let the number be {{{abcd}}} , with
{{{a}}}= the first digit,
{{{b}}}= the second digit,
{{{c}}}= the third digit, and
{{{d}}}= the fourth digit.
 
The "first digit is one-third the second" translates as
{{{a=b/3}}}<--->{{{b=3a}}} .
The "third is the sum of the first and second" translates as
{{{c=a+b}}} , so {{{system(c=a+b,b=3a)}}}--->{{{c=a+3a}}}<--->{{{c=4a}}} .
The "last is 3 times the second" translates as
{{{d=3b}}} , so {{{system(d=3b,b=3a)}}}--->{{{d=3*(3a)}}}<--->{{{d=9a}}} .
Since {{{a}}} and {{{d}}} are digits, the only option is {{{system(a=1,d=9)}}} .
Then,
{{{system(a=1,b=3a)}}}--->{{{b=3}}} and {{{system(a=1,c=4a)}}}--->{{{c=4}}} .