Tax Calculator/Sales Tax Formula The formula for calculating the sales tax on the goods or the service is: Selling price \( \times \) Sales tax rate When you want to calculate the total cost of a purchase, the formula is: Total sale amount \( = \) Selling price \(+\) Sales tax S...
Solution: The number of pencils is directly proportional to the cost. pencils. How To Solve Directly Proportional Questions? Example 1:F is directly proportional to x. When F is 6, x is 4. Find the value of F when x is 5. Example 2:A is directly proportional to the square of B. ...