In a row of girls, Rina and Mona occupy the ninth place from the right end and tenth place from the left end, respectively. If they interchanged their places, Rina and Mona occupy seventeenth place from the right and eighteenth place from the left, respectively. How many girls are there in the row ?
The correct option is B $$26$$
Since Rina and Mona changes the places, Rina 's position is same as Mona's earlier position.
The position is $$17th$$ place from the right and $$18$$th place from the left.
Hence, no. of girls is $$16+1+9=26$$.