2m÷m-n÷3mn÷m-n

To simplify the expression 2m ÷ (m - n) ÷ (3mn ÷ (m - n)), we need to follow the order of operations, which is Parentheses, Exponents, Multiplication and Division (from left to right).

First, let's simplify the expression inside the parentheses: 2m ÷ (m - n) ÷ (3mn ÷ (m - n)) = 2m ÷ (m - n) ÷ (3mn ÷ m - n)

Now, let's simplify the division within the parentheses: = 2m ÷ (m - n) ÷ (3mn ÷ m - n) = 2m ÷ (m - n) ÷ (3mn(m - n))

Next, let's divide by the common factor of (m - n): = 2m ÷ (3mn(m - n)) ÷ (m - n) = 2m ÷ (3mn(m - n)) × 1/(m - n)

Now, let's simplify the division by multiplying by the reciprocal: = 2m × 1/(3mn(m - n)) × 1/(m - n) = 2m/(3mn(m - n)(m - n))

Finally, we can simplify the numerator and denominator: = 2m/(3mn(m^2 - 2mn + n^2))

Therefore, the simplified expression is 2m/(3mn(m^2 - 2mn + n^2)).