Page 128 - ArithBook5thEd ~ BCC

Solution. Bills paid are losses, so we treat them as negative numbers; checks received are profits, counted
as positive numbers. The total profits are

350 . 6 5
461 . 0 0
+9 0 0 . 7 8

1, 7 1 2 . 4 3
and the total losses are
261 . 5 0
551 . 0 0
+ 7 8 . 7 0

89 1. 20
Affixing a negative sign to the total losses, we calculate the net profit (or loss) as the sum

1712.43 + (−891.20) = +(1712.43 − 891.20) = 821.23.

There was a net profit of $821.23 for the week.

4.5.1 Exercises
Find the sums or differences:

1. 680.48 + 56.09

2. 804.09 + 5.8409

3. 58.09 − 32.1
4. 4.09 + 0.38409

5. 14.093 − 6.39

6. 100 − 23.441

7. 830 − 16.61

8. 80 − 56.384
9. −13.38 + (−9.03)

10. −1001.36 + 909

11. −8.2 + (−198.5) + 8.2

12. 44 + (−5.5) + 28.8 + 36 + (−19.1) + (−8)

13. 18.50 + (−21.25) + (−69.95) + 13.50 + 79.99 + (−86.50)
14. Find the sum of 64.09, 15.3, 4, and 9.09.

15. The difference of 20 and the sum of 4.6 and 0.07

Page 128