A math club has a secret way of accounting, when the income of 300 yuan is recorded as - 240 yuan, when the use of 300 yuan is recorded as + 360 yuan How do they remember when they earn 100 yuan and when they spend 100 yuan? Writing rules thank you

A math club has a secret way of accounting, when the income of 300 yuan is recorded as - 240 yuan, when the use of 300 yuan is recorded as + 360 yuan How do they remember when they earn 100 yuan and when they spend 100 yuan? Writing rules thank you

300 - (- 240) = 600 yuan
Although the data recorded are different, there is still a difference of 600 yuan between 300 yuan spent and 300 yuan earned
-300 - (- 240) = - 60 yuan
It is equivalent to reducing the amount of money spent by 60 yuan and adding 60 yuan to the amount of money earned. That is to say, they take 60 yuan as the dividing point between the amount spent and the amount earned
Therefore, 100 yuan is recorded as - 40 yuan, while 100 yuan is recorded as + 160 yuan