In a row of girls, Rita and Monika occupy the ninth places from the right end and tenth place from the left end, respectively. If they interchange their places, Rita and Monika occupy seventeenth places from the right and eighteenth place from the left, respectively. How many girls are there in the row ?
Since Rita and Monika exchange places, so Rita's new position in the same as Monika's earlier position.
The position is 17th from the right and 10th from the left.
.'. Number of girls in the row = (16 + 1 + 9) = 26.