Sales tax was 7.5% how much did tammys lunch cost before tax if the tax on it was 0.72? define a variable and write an equation

The cost of Tammy lunch is 9.6 unit .

Step-by-step explanation:

Given as :

The percentage of sales tax = 7.5 %

The tax amount on cost = 0.72

Let the cost of Tammys lunch = x unit

So,

∵ The sales tax is applied on the cost

∴ 7.5 % of x = 0.72

Or, 0.075 × x = 0.72

Or, x =

∴    x  = 9.6 unit

Hence The cost of Tammy lunch is 9.6 unit .   Answer

since your problem is x^4 = 81, what you have to undeo is the "to the fourth power" part.

the inverse (opposite operation) of "to the fourth power" is "to the fourth root".

  (x^4) ^ ¼   = 81 ^ ¼  

  81 = 3^4     so (3 ^ 4) ^ ¼   =   3 ^ 1   = 3

by hand: (3 ^ 4) ^ ¼   =   3 ^ (4 x ¼) = 3 ^ 1   = 3   (when you take a power to a power, multiply the exponents.)

or, do it by calculator. one way of finding the fourth root is to use ^ (1/4)

step-by-step explanation: