This is a geometric sequence, so if you divide 192 by 144 you will find that the common ratio r is 4/3. This would make the equation an=144(4/3)^n-1. However, that's not one of the options. If you plug in some numbers, you can see that 3/4 (the reciprocal of 4/3) can work as well if it's 3/4^1-n. 4/3^-1=3/4 and n-1(-1)=1-n
