Answer:
The last option
Explanation:
The last option, so "Multiply the sum of 45 and 21 by 0.065. Add the result to the sum of 45 and 21"
You do this because when you multiply the sum of 45 and 21 by 0.065, you get the tax. Then you add the tax to the sum of 45 and 21 to get the total with tax