$1\mathrm{.}1$ Calculate the number of nights for the first transaction.

Copy and paste the formula down the column to calculate the nights for the other transactions.

$1\mathrm{.}2$ Calculate the "Room Total" for the first transaction.

Use an IF function to calculate a $10\%$ discount for any stay greater than or equal to $7$ nights.

Copy and paste the function down the column to calculate the room total for the other transactions.

$1\mathrm{.}3$ Calculate the "Add$-$On

$1\mathrm{.}4$ The manager would like

$1\mathrm{.}5$ In cell Q$14,$ use a SUMIF