快快教我maths

1. it is given that 168 and 338 are the 4th term and the 5th term of an arithmetic sequence respectively.Find the 3rd term and the 6th term of the sequence.

2. it is given that 12 and -48 are the 9th term and the 10th term of a geometric sequence respectively.Find the 8th term and the 11th term of the sequence.