I've spent so long trying to figure this out and I just CAN'T. I can see the relationship but I don't know how to actually calculate this through

Sn = u1(r^n-1) / 4-1

or Sn = n/2(2u1 + (n-1)d)

I tried calculating them both as geometric and as arithmetic but I can't figure out a consistent d or r?

Can someone help me please?

Thank you.