Answer:
17. (2/5)
19. (-7/3)
21. (2/3)
Explanation:
17.
5 5 1
- -------n + ------n = - ------
2 4 2
5 (2) 5 1 (2)
- -------n + ------n = - ------
2 (2) 4 2 (2)
10 5 2
- -------n + ------n = - ------
4 4 4
10 5 2
(- -------n + ------n = - ------) (4)
4 4 4
-10n + 5n = -2
-5n = -2
÷ -5 ÷-5
n = (2/5)
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19.
3 15 21
-------n - -------n = -------
2 4 4
3 (2) 15 21
-------n - -------n = -------
2 (2) 4 4
6 15 21
(-------n - -------n = -------) (4)
4 4 4
6n - 15n = 21
-9n = 21
÷-9 ÷-9
n = (-7/3)
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21.
1 5
- -------n - n = - -------
4 6
1 (3) 5 (2)
- -------n - n = - -------
4 (3) 6 (2)
3 10
- -------n - n = - -------
12 12
3 10
(- -------n - n = - -------) (12)
12 12
-3n - 12n = -10
--15n = -10
÷-15 ÷-15
n = (2/3)
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I hope this helps!