Several simple mathematical problems
1. It is known that the m-2n power of X, the M-1 power of Y and the 6-n power of - 3x, the cubic power of Y are the same kind of terms, and the value of M and N can be obtained
2. Given that the sum of the quadratic power of the polynomial 2x + my-12 and the quadratic power of the polynomial NX - 3Y + 6 does not contain X and Y terms, we can find the value of Mn
3. Party A bought a mobile phone from other places for 3820 yuan and sold it to Party B for 3880 yuan. Party B sold it to Party C for 3900 yuan and Party C sold it to Party A for a loss of 10 yuan. Party a sold it to Party B for 30 yuan cheaper based on the price that Party C sold to him. Party B sold it to Party C for 3840 yuan and Party C sold it to Party A for 3000 yuan, In the end, Party A gave it to an intermediary at the price of 3100 yuan. In this process, did Party A, Party B and Party C lose or earn? How much did they lose or earn?
Note: write the formula for each question!