Answer:
-5
Step-by-step explanation:
The common ratio is what you have to multiply one term by to get the next term.
so:
[tex]18 \times r = -90\\-90 \times r = 450[/tex]
where r is the common ratio
We can solve these equations:
-90 / 18 = -5
450/-90 = -5
therefore the common ratio is -5
