Overaping mahjong number

This is a game of Overaping mahjong number.The functions are:
Game Number 1:
What is the middle number between the sum of the two mahjong numbers above and below?（For example, the above sum is: 3. The total below is 5. So 4 is the middle number）
Game Number 2:
What is the result of subtracting the sum of mahjong numbers in the orange area from the sum of mahjong numbers in the blue area?\nAssuming the mahjong tiles in the blue area are 7 and 8; The mahjong tiles in the orange area are 1 and 2; So the result is: (7+8) - (1+2)