This is 10 points plz help ( NO LINKS ) ( ONLY ANSWER THIS IF YOU HAVE AN EXPLANATION AND IF YOU KNOW WHAT THE ANSWER IS)

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?

Abox contains 1 plain pencil and 4 pens. a second box contains 5 color pencils and 5 crayons. one item from each box is chosen at random. what is the probability that a plain pencil from the first box and a color pencil from the second box are selected? write your answer as a fraction in simplest form.

2x minus y equals 6, x plus y equals negative 3