3.12 I got the answer by dividing 25 by 8
(6 • 2 - 2x + 16) + (4 • 2 + 7x - 55)
(-2x + 16 + 6 • 2) + (7x - 55 + 4 • 2)
(-2x + 16 + 12) + (7x - 55 + 8)
-2x + 28 + 7x - 47
-2x + 7x + 28 - 47
5x + (-19)
5x - 19
So the answer is 5x - 19.
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;





1: ----> 2:00
2: ----> 4:45
3: -----> 2:15
4: -----> 4:41
5: -----> 16:15