Answer:
an = -4 * (-3)^ (n-1)
513560652
Step-by-step explanation:
We can find the common ratio
12/-4 = -3
r =-3
The explicit formula is
an =a1 r^(n-1)
an = -4 * (-3)^ (n-1)
We want the 18 th term
a 18 = -4 (-3) ^ 17
513560652
(4,4).........................
Choice C, because

So it's less than what she originally had (which isn't possible)
3+16=19,
3+20=23
So the correct answer would be 19 and 23