Are you solving for x or y?
5 because 25 divided by 5 is 5
The top number is 4 and t =1, so you need to replace t with 1, find the answer, then replace t with 2 through 4, then find the sum of all of them:
6^1-1 = 6^0 = 1
6^2-1 = 6^1 = 6
6^3-1 - 6^2 = 36
6^4-1 = 6^3 = 216
Sum = 1 + 6 + 36 + 216 = 259
The answer is B.
