I'm undecided on the age of the earth myself and don't believe there is any scientific measure that can provide an accurate age.
I think it's difficult to use the Bible to determine the age of the earth and as somebody else posted, we don't know how much time passed before the Fall; plus can we know for sure the genealogies listed are father/son? Having said that and from my own studies of the entire Bible, it seems to me God wants us to believe a literal account of creation.
Having followed the issue for years and read many books on the subject, I see no evidence for phyletic or gradual evolution. Sure there are many claims but it's the physical evidence that is lacking. Then there's the science of evolution and the politics of evolution and unfortunately, despite the many claims of those on the side of evolution, the politics of evolution trumps the science of evolution.
If the earth is old:
That argument falls apart quickly since Adam's age at death is given. Unless you don't think the time before the fall counts toward that age.
But hey, don't worry about what the Bible says, make it fit what man says. Man is the ultimate authority, after all.
What about the age of the universe? The physics of our galaxy can be studied independent of evolutionary life cycles on Earth. Light from distant stars alone discounts a young universe.