3 /5 : ( − 4 /15 ) =

To solve this mathematical expression, we need to follow the order of operations, which is PEMDAS in Russian:

1. Parentheses (Скобки)
2. Exponents (Степени)
3. Multiplication and Division (Умножение и Деление)
4. Addition and Subtraction (Сложение и Вычитание)

Now, let's calculate 3/5 - (-4/15).

To subtract fractions, we need a common denominator: 3/5 - (-4/15) = (9/15) - (-4/15).

Using the same denominator, we get: 9/15 + 4/15 = 13/15.

Therefore, the result of the expression 3/5 - (-4/15) is 13/15.

If you have any more questions or need further clarification, feel free to ask!