Question 484946
Let xy is a number then we can write it {{{10x+y}}}
The sum of digits is {{{x+y}}}, the number is 4 times the sum of it's digits, so {{{10x+y=4(x+y)}}}
The difference of the digits is 4, so {{{abs(x-y)=4}}}
The sustem 
{{{system (10x+y=4(x+y), abs(x-y)=4)}}}
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1. {{{system (10x+y=4(x+y), x-y=4)}}}
{{{system (10x+y=4x+4y, x=4+y)}}}
{{{system (6x-3y=0, x=4+y)}}}
{{{system (6(4+y)-3y=0, x=4+y)}}}

{{{24+6y-3y=0}}}
{{{3y=-24}}}
{{{y=-24/3=-8}}}exterior root

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2. {{{system (10x+y=4(x+y), x-y=-4)}}}
{{{system (6x-3y=0, x=-4+y)}}}
{{{system (6(-4+y)-3y=0, x=-4+y)}}}
{{{-24+6y-3y=0}}}
{{{3y=24}}}
{{{y=24/3=8}}}
{{{x=-4+8=4}}}
The number is 48