Answer:
See below in bold.
Explanation:
It looks like the third term should be -36.
The sequence is geometric.
The common ratio is -54/-81 = -36/-54 = -24/-36 = 2/3 .
The sum of the first 5 terms is
(-81) * (1 - (2/3)^5) / (1 - 2/3)
= -81 * 211/243 * 3
= -211.