Thinking Mathematically (6th Edition)

Published by Pearson
ISBN 10: 0321867327
ISBN 13: 978-0-32186-732-2

Chapter 5 - Number Representation and Calculation - Chapter Summary, Review, and Test - Review Exercises - Page 244: 18


-7 - 8 = -15 The Answer is -15

Work Step by Step

The problem -7 - 8 is actually saying that we subtract 8 from -7. This will give us an even larger in magnitude negative number, A lot of times we will rewrite this type of problem like this: -7 - 8 = -7 + (-8), because subtracting is really just adding a negative.. Then -7 + (-8) is -15. We add the number parts and since both are negative, we make sure to put the negative sign on our answer. Some more concrete (real world applications of this problem deal with money or temperatures.) For example. If it is -7 degrees outside today and the temperature drops another 8 degrees (this is a change of -8 degrees, we go down to -15 degrees..
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