Ignore the x's pls pls pls help

Somone me i want to know what 18 hours out of 24 hours in a fraction

Steve wants to develop a way to find the total cost of any item including sales tax. the sales tax in his city is 6%. his friend jenna writes the expression x + 6x where x is the cost of the item. explain whether her expression is correct based on the situation.

The vet charges $45 for an office visit and $10 for each vaccination your dog needs. write an eaquation