3/15
1/3 of 3/5 is the same as multiplying
if it were only 1 acre it would look like 1/3 x 1 so for 3/5 of an acre, it is
(1/3) x (3/5)
remember, multiplying fractions is numerator to numerator, and denominator to denominator.
so (1/3) x (3/5) = 3/15