This is just like the other question you asked.
The only difference is that we don't have number like 5th or 6th term.
We are looking for nth term instead
The initial term is the same as the first term which is equal to a, and a = 7.5
Common ratio = 7
Use the same formula I reminded you of earlier
plug in your number
an = 7.5 * 7 ^( n-1)
Practice more examples to master this...