Answer:
The formula to determine the total bill including taxes, i.e. grand Total =
"subTotal" + ("taxRate" * "subTotal").
Another formula is:
"grandTotal" = ("subTotal" * 1 +"taxRate")
Step-by-step explanation:
The above stated formulas produce the same outcome. The first formula computes the tax amount and adds it to the subtotal before arriving at the grand total. The second formula goes straight to compute the total bill without showing the tax amount. It applies the tax factor (1 + "taxRate") to the "subTotal." All two formulas are valid. However, I prefer the second formula to the first, as it is very straight forward.