Am i doing this right someone plz me with this what’s the answer and the work for this

Ahigh definition tv cost $800 with a down payment of 2/5 of the cost. how much is left to pay, in dollars after the down payment has been made?

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 collection of beautiful oil paintings currently on display at an art gallery well defined; set not well defined; not a set