1. CD = 6, DE = x + 10, CE = 3x 1. given
2. CD + DE = CE 2. segment addition postulate
3. 6 + (x + 10) = 3x 3. substitution
4. x + 16 = 3x 4. simplify (add like terms)
5. 16 = 2x 5. subtraction property of equality
6. 8 = x 6. division property of equality
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DE = x + 10
= (8) + 10
= 18
Answer: DE = 18
