Which of the following shows the polynomial below written in descending order

Which is an equation for the nth terms of the sequence 12,15,18,21

Abag has more green balls than blue balls, and there is at least one blue ball. let bb represent the number of blue balls and let gg represent the number of green balls. let's compare the expressions 2b2b and b + gb+g. which statement is correct? choose 1

How do you use the elimination method for this question? explain, because i really want to understand!