Question 503211
Let the digits be a,b,c, and d in descending order
so that d is the units digit
given:
(1) {{{ d + c = 8 }}}
(2) {{{ b = 4 }}}
(3) {{{ d = 4 }}}
(4) {{{ a + b + c + d = 18 }}}
--------------------
{{{ a + 4 + c + 4 = 18 }}}
{{{ a + c + 8 = 18 }}}
{{{ a + c = 10 }}}
Subtract (1) from this result
{{{ a + c = 10 }}}
{{{ -d - c = -8 }}}
{{{ a - d = 2 }}}
{{{ a - 4 = 2 }}}
{{{ a = 6 }}}
and, since
{{{ a + c = 10 }}}
{{{ 6 + c = 10 }}}
{{{ c = 4 }}}
The number is 6444