I am not sure how to use a model to represent this, but I can still help you solve this.
The new price is $1,440.
First find out how much money the refrigerator was marked up by:
1,200 x 0.2 = 240
Now add to the original amount:
1,200 + 240 = 1,440
The new price is $1,440 for the refrigerator. I hope this helps, and sorry I couldn't model it.