What is the 4 digit number...
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...in which the first digit is one fifth of the last,...
That narrows it down to
1--5
...and the second and third digits are the last digit multiplied by 3?...
The last digit is 5, multiplied by 3 is 15, so 15 goes in the middle,
so the number is
1155
The sum of the digits is 12
That checks: 1+1+5+5=12.
Answer: 1155
Edwin
