Question

The ${17}^{th}$ term of an $A.P$ succeed ${10}^{th}$ term by $7$. Find common difference $d$ ?

Answer 1

$a_{10}=a_{17}+7$

$a+9d=a+16d+7$

$9d-16d=7$

$-7d=7\Rightarrow d=-1$