Answer:
Answer below.
Explanation:
1. a + 19 | 10 + (a + 9) = a + 19
10 + 9 = 19
a + 19
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2. (C + 2/3) + 1/2 = C + 7/6
2/3 = 4/6
1/2 = 3/6
4/6 + 3/6 = 7/6
C + 7/6
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3. 5 (4n) = 20n
5 x 4n = 20n