For each part A through D below, the idea is to find the common factor between the terms, which you'll then use the distributive property to pull out.
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Part A
3x + 18 = 3(x+6)
Note how we pulled out a 3. If we distribute it back in, we end up with 3x+18 again. The other problems are done in a similar fashion
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Part B
2x - 14 = 2(x - 7)
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Part C
6x + 4 = 2(3x + 2)
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Part D
9x - 15 = 3(3x - 5)