40
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
What is the value of $x + y$ if the sequence $2, ~6, ~10, \ldots, ~x, ~y, ~26$ is an arithmetic sequence?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
40
What is the value of $x + y$ if the sequence $2, ~6, ~10, \ldots, ~x, ~y, ~26$ is an arithmetic sequence?
train