Question 628806
The number has the form abcd.
You are told d = 1 and a = 5*d = 5
So far we have 5bc1
You are told b=c. So now we have
5bb1
Finally you are told the sum of the digits is 10
So
{{{5+ 2b + 1 = 10}}}
{{{6 + 2b = 10}}}
{{{2b = 10-6}}}
{{{2b = 4}}}
{{{b = 2}}}
The number is
5221