(3-2)-1=0
3-(2-1)=2
Boom! Done
Step-by-step explanation:

Answer:
b
Step-by-step explanation:
Answer:
20 lbs
Step-by-step explanation:
2/5ths of the food would be 20 pounds because:
2/5 * 50 = 20
2/10ths of the food would be 10 pounds because:
2/10 * 50 = 10
If we add those two together, we would get the total amount that the dog ate, which would be 30 pounds. SInce the dog ate 30 pounds of food out of the 50 pounds, there would be 20 pounds left in the bag at the end of two months:
50- ( 20+ 10) = 20
Estimation:
23 --> rounded to 20
71 --> rounded to 70
70 + 20 = 90. I rounded both numbers down so the exact sum must be only a little greater than my estimate.