math
posted by dj .
the number of my hunderds plus the number of my thousandsin 3. the number of my tens is 7 times the number of my hundreds. the number of my ones is 3 times the number of my thousands. allmy digits are differnt. what number am i ?

The number is abcd
b+a = 3
c = 7b
d = 3a
Since c=7b, b = 0 or 1, or else the product would be > 10
b is not 0, or 7b would also be 0, and all digits are different. S, we now have
a17d
b+a=3, so a = 2:
217d
d=3a, so d=6 and our number is
2176