Since Kashish and Mona interchange places, so Kashish's new position (13th from left) is the same as Mona's earlier position (6th from right).
So, number of children inn the queue = (12 + 1 + 5) = 18.
Now, Mona's new position is the same as Kashish's earlier position i.e., fifth from left.
.'. Mona's position from the right = (18 - 4) = 14th.