${7^{th}}$ term of an $A.P.$ is $40$, then the sum of first $13$ terms is
${7^{th}}$ term of an $A.P.$ is $40$, then the sum of first $13$ terms is
- A
$53$
- B
$520$
- C
$1040$
- D
$2080$
Similar Questions
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The number of terms common to the two A.P.'s $3,7,11, \ldots ., 407$ and $2,9,16, \ldots . .709$ is
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