To subtract fractions in Russian, we need to have a common denominator first. Let's find the common denominator for 1/3 and 3/5.
The least common multiple of 3 and 5 is 15.
Therefore, 1/3 is equivalent to 5/15 (multiply the numerator and denominator by 5).
And 3/5 is equivalent to 9/15 (multiply the numerator and denominator by 3).
Now, we can subtract the fractions:
5/15 - 9/15 = (5 - 9) / 15 = -4/15
So, the result of the expression 1/3 - 3/5 is -4/15.