Can some one please help me and explain how you got the answer?

If a and −a are numbers on the number line, which expression must give the distance between them? a) 0 b) a c) |2a| d) |a|

Find the missing factor. write your answer inexponential form.9^2=9^4×

Will give brainliest figure abcd is rotated by 180 degrees about the origin in the counterclockwise direction to obtain figure a′b′c′d′: which statement best compares the lengths of the sides of the two figures? length of ab = length of c′d′ length of cd = length of a′b′ length of cd = length of b′c′ length of ab = length of a′b