If 7 times the 7^th term of an AP is equal to 11 timesits 11^th term then find its 18^th term

If 7 times the 7^th term of an AP is equal to 11 timesits 11^th term t

1.	If 7 times the 7^th term of an AP is equal to 11 timesits 11^th term then find its 18^th term
Answer» 7(a+6d)=11(a+10d)7a+42d=11a+110d7a-11a=110d-42d-4a= 68d a=-17da+17d=0a+(18-1)d=018th term = 0