The first term of a geometric sequence is 640, and the common ratio is (1/2). What is the 8th term of the sequence?

A: 20
B: 2.5
C: 10
D: 5

The answer is D: 5

Just copying this over just in case others with similar questions turn this up in search results rather than the other, haha!
When you multiply or divide a negative by another negative, you get a positive. When it is a negative and a positive, it remains negative.
Assuming your question simplified into a equation (or number form? Been a while, haha!) is 32÷-2÷(-16÷4), it would end as a positive. Because you first divide the positive 32 by a negative 2, you get a negative. Because -16÷4 is in parenthesis, it is done because following the rest of the equation (P.E.M.D.A.S.!), it would be 32÷-2÷-4. Going from left to right, as you should, it results in a negative being divided by another negative, so you get a positive. 32÷-2÷(-16÷4) = 32÷-2÷-4 = -16÷-4 = 2!