Since only you y-value is missing, I think all you have to do here is just plug in the x value. So, it would be y = 4 - 3(-3).When you solve it, you should get 13.To check, plug both values into the equation and see if they come out to be equal. :D
A coordinate is shown as (x,y)
So if -3 is shown as x, then y is the unknown.
In other words...
Put -3 in for x in the equation-
y= 4 - 3(-3)
y=4 + 9
The solution to this would be (-3, 13)