Question

The number of common terms to the two sequences $17, 21, 25$, ___, $417$ and $16,21,26$, ____, $466$ is

Answer 1

Common terms will be $21, 41, 61$, ______
$21 + (n-1) 20 \le\,417$
$\Rightarrow \, n \le 20.8$
$\Rightarrow n = 20$