Answer:
2
x
6
Explanation:
action figure cost = $3 <- constant
trading card cost = $6(# of trading cards) = 6x
to get poster: spend at least 15, no more than 39
15
3+6x
39
split into two equations
3+6x
39
3+6x
15
solve for x for each
3+6x
39
6x
36
x
6
3+6x
15
6x
12
x
2 or 2
x
combine equations back together
2
x
6