Answers

2016-02-03T18:49:56+05:30
L=a+(n-1)d
31=15+(n-1)2
31=15+2n-2
31-13 = 2n
n = 18/2
n = 9
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2016-02-03T18:52:37+05:30
I=a+(n-1)d
31=15+(n-1)2
31=15+2n-2
31+2=15+2n
33-15=2n
∴n=18/2
∴n=9

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