Since an integer is any whole (not fractional) number on the number line, all you have to do is move to the left however many units you're subtracting by <em>from </em>the point given. Say the problem is 3 - 7. This means we start at 3, and move to the left 7 units, which lands us at -4. However, if we had a problem like 12 - (- 2), the two negatives would cancel out, meaning we will move to the <em>right</em> 2 units on the number line, or 12 + 2, which is 14. Some other examples are:
-12 - 4, (you should get -16)
3 - 8, ( you should get -5)
16 - (- 3), ( you should get 19)
I hope these tips helped you out! I know that when I first had to subtract integers, using a number line really helped me out. Eventually, it'll just be a natural thing. :D
