What is the variance of 4,7,5,9? how do i find the answer?

Desmond wants to sell his car that he paid $8,000 for 2 years ago. the car depreciated, or decreased in value, at a constant rate each month over a 2-year period. if x represents the monthly depreciation amount, which expression shows how much desmond can sell his car for today? 8,000 + 24x 8,000 − 24x 8,000 + 2x 8,000 − 2x

The square pyramid has a volume of 441 cubic inches. what is the value of x? 1/7x is the height x is the base

What is the best way to answer questions with a x expression in the question. for example 3x + 10x=?