Answer:
B
Step-by-step explanation:
We are given that:

Are consecutive terms of an arithmetic sequence.
And we want to determine the common difference <em>d</em>.
Recall that for an arithmetic sequence, each subsequent term is <em>d</em> more than the previous term.
In other words, the second term is one <em>d</em> more than the first term. So:

And the third term is two <em>d</em> more than the first term. So:

We can isolate the <em>d</em> in the first equation:

As well as the second:

Then by substitution:

Solve for <em>x:</em>
<em />
<em />
<em />
The isolated first equation tells us that:

Therefore:

Our final answer is B.