First step you would have to do would be to times 35 by 12 to see how much you would have to pay for 12 months.
35 x 12 = 420
Then, as you said, you a down payment of 600 so then you'd add.
600 + 420 = 1,020.
So the total cost of the computer would be $1,020.
For y=3x+4, you would put 4 on the y-intercept and from that point you go up 3 and right 1 and then plot the second point.
For y=-x-4, you would put -4 on the y-intercept and from that point go down 1 and right 1 and then plot the second point.
