15% of 240 grams helppp

Ineed to know the answer to this algebra question.

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|

Marion has a bicycle that she is planning to take for a ride. the rim of the rear wheel lies 41 cm from the center of the wheel. the tire itself has a thickness of 3 cm. in order for marion to ride her bicycle 96,712 cm approximately how many rotations will the rear wheel make?