Well if you have a problem like -6 + 7, then you can use one color of algebra tiles(atls) for the negative and another color for positive. Take yellow for negative and red for positive for an example. You have 6 yellow and 7 reds. You want to make as many pairs of one red and one yellow. You can make a total of 6 pairs and a red left over. Since red is positive an there is only one, your answer is 1.
Hope i helped
