Then get the correct difference:15-3.7 =11.3.
(2) Reverse thinking mode: If 3 in the meiotic unit is regarded as 8, it will be reduced by 5, and if 7 in one tenth is regarded as 1, it will be reduced by 0.6.
The correct difference is 6.9+(8-3)-(0.7-0.1) =11.3.