Answer
215
Work Step by Step
$S_{n}=\dfrac {2a_{1}+\left( n-1\right) d}{2}\times n;d=14-11=11-8=3\Rightarrow S_{10}=\dfrac {2\times 8+\left( 10-1\right) \times 3}{2}\times 10=43\times 5=215$
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