Imagine a merchant has 126 bottles of wine in her inventory. She wants to sell 31 of them to a customer. Using a counting board, how would she calculate the number of bottles she will have left in her inventory if she makes this sale? A
The merchant begins with 157 pebbles on the right side of the counting board. 31 pebbles are moved to the left side from the right side. The total number of pebbles remaining on the right side is the number of bottles she will have in her inventory if she makes the sale.

B
The merchant begins with 95 pebbles on the left side of the counting board. 31 pebbles are added to the left side of the counting board. The total number of pebbles on the left side is the number of bottles she will have in her inventory if she makes the sale.

C
The merchant begins with 126 pebbles on the left side of the counting board. 31 pebbles are moved from the left side to the right side. The total number of pebbles remaining on the left side is the number of bottles she will have in her inventory if she makes the sale.

D
The merchant begins with 126 pebbles on the right side of the counting board. 31 pebbles are moved to the left side from the right side. The total number of pebbles remaining on the right side is the number of bottles she will have in her inventory if she makes the sale.

E
The merchant begins with 95 pebbles on the right side of the counting board. 31 pebbles are added to the left side of the counting board. The total number of pebbles on the right side is the number of bottles she will have in her inventory if she makes the sale.