In a row of boys, if A who is tenth from the left and B who is ninth from the right interchange their positions, A becomes 15th from the left. How many boys are there in the row?
A21
B23
C28
D32
Answer:
B. 23
Read Explanation:
A's new position is 15th from the left. But this is the same as B's earlier position which is 9th from the right.