We can easily find the change in any value usually by subtracting the number with the smaller absolute value from the number with the larger absolute value, based on the way the question is worded. This question, however, allows us to use this.
For question A, all we have to do is subtract 6.4 from 13.6. We then have the equation 13.6 - 6.4. That will end us up with 7.2. Since we are going from a larger positive number to smaller positive number, we will have to turn our result into a negative number because we are moving backwards and not going forwards. We have the answer of -7.2. Also noting that the question asks for an average, we can round -7.2 down to -7.
For question B, we can do the same things we did with question A. We subtract -3.5 from 13.6. With that said, we then have the number 17.1. Since the question is asking for the change from a positive number to a negative number, then we will have to turn 17.1 into a negative number which is -17.1. Also, noting that the question asks for an average, we can round -17.1 down to -17.
