Before there was any life on Earth, which gas was absent from the ancient atmosphere? A. nitrogen
B. ammonia
C. oxygen
D. methane

please answer lol

What are the measures of ∠a, ∠b, ∠c and ∠d? explain how to find each of the angle measure.

Abag contains 10 white golf balls and 6 striped golf balls. a golfer wants to add 112 golf balls to the bag. he wants the ratio of white to striped gold balls to remain the same. how many of each should he add?

The width of a rectangle is half as long as the length. the rectangle has an area of 18 square feet. what are the length and width of the rectangle?