Which is an equation of the line with slope -4 and a y-intercept 7

On this graph, the bottom horizontal line represents an ineffective price floor set above equilibrium. an effective price floor set below equilibrium. an ineffective price ceiling set above equilibrium. an effective price ceiling set below equilibrium.

Quick i have a question on my exam review and i have my exam tmr. how does the taiga region change as your cross canada. make sure it’s canada!you : )

Can someone me with this plz? ! i'm putting 20 points on it!