WASHINGTON (AP) – President-elect Joe Biden turned 78 Friday, and he’ll soon take the reins of a politically fractured nation facing the worst public health crisis in a century, high unemployment and a reckoning on racial injustice. As Biden wrestles with those issues, he will be attempting to accomplish another feat: demonstrating to Americans that age is but a number. Biden will enter office as the oldest president in the nation’s history, displacing Ronald Reagan. Reagan left the White House in 1989 when he was 77 years, 349 days old.