For Salaries and Wages payable, why to use this formula, and why subtract the days of sick.

Sarasota Company began operations on January 2, 2019. It employs 9 individuals who work 8-hour days and are paid hourly. Each employee earns 10 paid vacation days and 8 paid sick days annually. Vacation days may be taken after January 15 of the year following the year in which they are earned. Sick days may be taken as soon as they are earned; unused sick days accumulate. Additional information is as follows. Actual Hourly Wage Rate Vacation Days Used by Each Employee 2019 2020 0 9 Sick Days Used by Each Employee 2019 2020 6 7 2019 $7 2020 $8 Sarasota Company has chosen to accrue the cost of compensated absences at rates of pay in effect during the period when earned and to accrue sick pay when earned. (To record vacation time paid) Salaries and Wages Expense 1296 Salaries and Wages Payable 2736 Cash 4032 (To record sick leave paid) Salaries and Wages Payable 9 employees $7/hr. 8 hrs./day (8-6) days 9 employees x $8/hr. x 8 hrs./day x (7-2) days $1,008 + 2,880 $3,888 Sarasota Company began operations on January 2, 2019. It employs 9 individuals who work 8-hour days and are paid hourly. Each employee earns 10 paid vacation days and 8 paid sick days annually. Vacation days may be taken after January 15 of the year following the year in which they are earned. Sick days may be taken as soon as they are earned; unused sick days accumulate. Additional information is as follows. Actual Hourly Wage Rate Vacation Days Used by Each Employee 2019 2020 0 9 Sick Days Used by Each Employee 2019 2020 6 7 2019 $7 2020 $8 Sarasota Company has chosen to accrue the cost of compensated absences at rates of pay in effect during the period when earned and to accrue sick pay when earned. (To record vacation time paid) Salaries and Wages Expense 1296 Salaries and Wages Payable 2736 Cash 4032 (To record sick leave paid) Salaries and Wages Payable 9 employees $7/hr. 8 hrs./day (8-6) days 9 employees x $8/hr. x 8 hrs./day x (7-2) days $1,008 + 2,880 $3,888