Answer:
2 [tex]\leq[/tex] x [tex]\leq[/tex] 6
Step-by-step 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 [tex]\leq[/tex] 3+6x [tex]\leq[/tex] 39
split into two equations
3+6x [tex]\leq[/tex] 39
3+6x [tex]\geq[/tex] 15
solve for x for each
3+6x [tex]\leq[/tex] 39
6x [tex]\leq[/tex] 36
x [tex]\leq[/tex] 6
3+6x [tex]\geq[/tex] 15
6x [tex]\geq[/tex] 12
x [tex]\geq[/tex] 2 or 2 [tex]\leq[/tex] x
combine equations back together
2 [tex]\leq[/tex] x [tex]\leq[/tex] 6
