Explanation:
In a GP, there is a common ratio between the terms.
8 / (-16/5) = 8 * (-5/16) = -2.5
-20 / 8 = -2.5
We can see that every new term is -2.5 times bigger than the previous term.
Hence to find the next term,
we multiply -20 by -2.5:
(-20)(-2.5) = 50.
Hence 50 should go into the box.