Add or Subtract?

[lmallen30]

HI, I'm trying to help my son with his homework. The teacher posts an Answer Key to check homework for accuracy. I am looking at the answer key and trying to understand if it might be incorrect.
I would have thought we would subtract the area of the triangle from the rectangle, not add it. (112 - 12 = 100, not 112+12)
If anyone could please explain why we should add it, I would appreciate it!
Thanks!

 

[mmm4444bot]

Add or Subtract?​

Subtract. (The triangular piece is removed.)

I've made the same sort of mistake (i.e., doing something backwards), when tired or distracted.

PS: If a triangular piece were to have been sewn onto the rectangle, then we would add to get total area of fabric required.

 

[lmallen30]

Makes sense. Thanks so much for taking the time to answer!

 

[HallsofIvy]

The rectangular piece of paper has area 8(14)= 112 square inches.

Cutting off a piece will NOT make it larger!

 

[Steven G]

The rectangular piece of paper has area 8(14)= 112 square inches.

Cutting off a piece will NOT make it larger!

But if you cut it correctly you can get a second copy of it!

 

[Otis]

if you cut it correctly you can get a second copy of it!

Can you show me how to do that with dollar bills?

?

 

[Steven G]

Can you show me how to do that with dollar bills?

?

Why not with $100 bills?

 

[Otis]

Why not with $100 bills?

Oh, I never see those.