If they are in the same line yes. If they aren't then its considered non-collinear.
-3 because it reduced -3 every hour of you divide -12 by 4 you will get -3 which is the average
4 + 5t < 19
Subtract 4 from both sides
5t < 19 - 4 or 5t < 15
Divide both sides by 5
t < 3