Please help me i dont get it

Can someone check if i did this correct. it’s number 4 if you’re wondering.

What is the 9th term in the geometric sequence described by this explicit formula? an=-6. (2)(n-1) apex

Asunflower was 20 1/2 inches tall. over the next 6 months, it grew to a height of 37 inches tall. what was the average yearly growth rate of the height of the sunflower? ? plz write a proportion to solve i will give you 100 points