The task is to generate the correct answer for a given math problem.

[Q]: Problem: a man rows his boat 110 km downstream and 90 km upstream , taking 3 hours each time . find the speed of the stream ?
[A]: 3.5


[Q]: Problem: robert ' s salary was decreased by 20 % and subsequently increased by 20 % . how much percentage does he lose ?
[A]: 4 %


[Q]: Problem: if n = ( 33 ) ^ 40 + ( 43 ) ^ 33 what is the units digit of n ?
[A]:
1