What type of list is shown with these numbers? 125, -50, 20, -8

so.. notice, if you divide a term by the term before it, you end up with a quotient of -2/5

that means, to get from one number to the next, you simply multiply that number by some value, in this case -2/5, it cold be anything, that common multiplier is called the "common ratio"

and lists like this one, are "geometric sequences"