what is the common difference between the elements of the arithmetic sequence below? -18, -22.5, -27, -31.5…

Explanation:

Step1: Recall common - difference formula

The common difference $d$ of an arithmetic sequence is $d=a_{n + 1}-a_{n}$, where $a_{n+1}$ and $a_{n}$ are consecutive terms.

Step2: Select two consecutive terms

Let $a_{n}=-18$ and $a_{n + 1}=-22.5$.

Step3: Calculate the common difference

$d=-22.5-(-18)=-22.5 + 18=-4.5$

Answer:

$-4.5$