Is this a contradiction or am I reading it wrong? Genesis 5:28

[Anomalocaris]

Solved!

Clearly 802 years means Lunar-years, where 12 lunar cycles is the Lunar-year, while 777 is number of Solar-years. (777 * 365.24 / (29.5 * 12) ~ 802)

The writers were clearly astronomers, and put apparent contradictions like this in the text just to trip up the unfaithful

Checkmate, atheists! 

Except of course a consistent 12 lunar synodic months was not the lunar years used by the hebrews.     A Hebrew Lunar year has variable number of month so it is periodically brought back into rough alignment with the solar year.     So the length of 777 solar years would have very close to the length 777 Hebrew lunar years,  to be within about 30 days to be exact.     The 25 year discrepancy between 777 and 803 is certainly far outside error bounds, except may be to god whose perfection, as neo informs us, relies on human pretending his errors are not errors.