When writing the range or domain of a function, how do i know when to use () or []?

What is the solution to the equation? k/6.4=8.7 2.3 5.568 15.1 55.68

Luke started a weight-loss program. the first week, he lost x pounds. the second week, he lost pounds less than times the pounds he lost the first week. the third week, he lost 1 pound more than of the pounds he lost the first week. liam started a weight-loss program when luke did. the first week, he lost 1 pound less than times the pounds luke lost the first week. the second week, he lost 4 pounds less than times the pounds luke lost the first week. the third week, he lost pound more than times the pounds luke lost the first week.

Acar loses a quarter of its value every year. it is originally worth $35,000. to the nearest dollar, how much will the car be worth in 8 years?