Final answer:
To calculate the total cost of a double room including tax, add $20 to the cost of a standard room and then apply the tax rate to this sum. Due to the lack of specific figures for the cost of a standard room and tax rate, we can't determine an exact numerical total.
Step-by-step explanation:
To find the total cost of a double room at a hotel, including tax, we need to know the cost of a standard room and the tax rate. Since we are not provided with this information, we'll use variables to represent them. Let x be the cost of a standard room and y be the tax rate.
The cost of a double room is $20 more than the cost of a standard room so the price before tax for a double room is x + $20. To calculate the tax on the double room, we need to convert the tax rate y from a percentage to a decimal and then multiply it by the cost of the double room:
y/100 × (x + $20)
The total cost of the double room, including tax, is the sum of the cost of the double room and the tax applied to it:
Total cost = (x + $20) + (y/100 × (x + $20))
Note: Since we don't have the actual numbers for x and y, we cannot compute a numerical total. If the actual figures are provided, we could plug them in to find the final total cost.