Regrouping in subtraction means that if you can't subtract because the digit on the bottom has a greater value than the digit on the top (such as 3-6)m so in this case you would have to regroup twice.
Answer:

Step-by-step explanation:

Answer:
1:+35
2:-270
3:-12
4+19
5:-15
6:-25
Step-by-step explanation:
The perimeter of the carpet is determined by its dimensions so the dimensions of the room are irrelevant to the question.
P=2(x+y) where x and y are the dimensions, here x and y equal 9 and 12 ft so
P=2(9+12)
P=2(21)
P=42 ft