30+8/5=31.6 you have to break the whole question down to get the answer.
ANSWER

EXPLANATION
The sum of the first
terms of a geometric sequence is given by;

Where
, is the number of terms and
is the first term.
When
, we have
, we get;





Since an equilateral triangle has 3 equal length sides, and in this case the total of these 3 sides is 24cm, the length of one side is 24/3 = 8cm
A is the answer because its right according to the chart