Answer:
The best estimate for 43x78 is 40x80
Step-by-step explanation:
43 rounded to the nearest ten is 40.
78 rounded to the nearest ten is 80.
The answer to 40x80 is 3200
Answer:
B. 
Step-by-step explanation:






I am not completely sure how to name faces, but I will name them using all four points.
Faces DCBA
Faces BFGC
Faces HGFE