Question

Q.19

Answer 1

Let a annd a' be the first terms and d be the common difference of two A.P.s

Given, 

`t_50-t'_50=50`

`⇒ (a+49d)-(a'-49d)=50`

`⇒ a-a'=50`

Now, 

`t_80-t'80=(a+79d)-(a'-79d)`

            `   =a-a'`

            `=50`