427051:839-390912:768+252000:1260+249249:249=?

Question

427051:839-390912:768+252000:1260+249249:249=?

Answer 1

1)427051:839=509   2)390912:768=509   3)252000:1260=200   4)249249:249=1001   5)509-509=0   6)0+200=200  7)200+1001=1201