Answer:
1) -12 + 5 = -7, to know if the answer will be positive or negative we see the biggest number, if the biggest number is positive the answer will be positive and if it is negative the answer will be negative, in this case 12 is bigger than 5 and it is negative. The model is in the attachment.
2) 20 yards gained, you found the answer by adding all the gained yards and subtracting all the lost yards.
Explanation:
1) this question is asking how to solve -12 + 5 which is equal to -7. The number line model is in the attachment
2) To solve number 2 we have to add all the yards they gained and subtract all the yads they lost:
7-3+15-2-3+6 and this is equal to 20 yards gained. We found this answer by adding and subtracting. A number line model is in the attachment.