Untitled

Price
  ^
3000|          D\                <-- demand line (hits P=3000 at Q=0)
    |            \ 
    |             \
1500|--------------• E (Q=6000, P=1500)  equilibrium
    |              \
1200|--------------+-----------------   Price ceiling at $1200
    |               \   shortage (QD above QS)
 500|       S -------• (Q_S at P=500 -> Q=0)
    |
    +----------------------------------> Quantity
         0   4200   6000   7200    12000