"what percentage of earth's total lifetime is habitable? "

The correct answer is - 82.61%

Our planet is estimated to be 4.6 billion years old, while the first life on our planet has risen around 3.8 billion years ago. So we have a situation where 3.8 billion years of Earth's geological history it has been habitable. To get to the percentage and correct result we need to multiply 3.8 (billion) by 100 (the number of total percents), and than divide the result with 4.6 (billion).

3.8 x 100 = 380

380 / 4.6 = 82.61%

for e2020. the answer would be some directions from the mountain range so we can find mt. whitney. to locate which direction is north, you should use a   compass. this would not only find mt. whitney, but also becuase of this long paragraph you would get points because it's not like anyone actually reads your work becuase once they read the first sentence it sounds dumb enough to not read becuase i'm not good at answering this but the answer is compass for your benefit.

for e2020 ; -;