f(n) be the largest prime divisior of n it is required to given example to explain whether x < y but f(x) > f(y)
So, take an example and explain.
take x = 5 and y = 16
for x = 5 the largest prime divisor of 5 is 5
so, f(5) = 5
for y = 16 the largest prime divisor of 16 is 2
so, f(16) = 2
5<16 but 5>2 that is
therefore, the given statement is possible.