RE: Math Brain Teasers 15:: Can You Find The Connection Between The Given Equations?

The answer is 21978. I figured out that only 2 and 8 are the numbers which when multiplied by 4 can give 8 and 2 which would be a reversible number. Then I just hit and trial the number D starting from 9 towards 0 and somehow after a long time, got the answer. That was a difficult one!!