738 contains wrong numbers, so:
6x0
614
206
xxx
xx0
xx0 number at the wrong spot. The 0 must be at spot 1 or 2
206 number at the wrong spot, that must be the 0, so the 0 is at spot 1 : 0--
6x2 number at the right spot. Spot 1 is taken, so the 2 is at spot 3 : 0-2
Now we know that the 6 isn't in there, so with this knowledge:
xx2
x14
xxx
xxx
xxx
x14 number at the wrong sspot. Only spot 2 is free, so the 4 needs to go to the 2nd spot : 042
042 is the answer