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DF= 78, DE = 5x -9, EF = 2x + 10, find DE.

User Mike Richards
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2 Answers

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DF = 78, DE = 5x - 9, EF = 2x + 10, find DE.

Solve for x first.

5x - 9 + 2x + 10 = 78

7x + 1 = 78

7x = 78 - 1

7x = 77/7

x = 11

Then substitute the value of x to find DE.

DE = 5x - 9

5(11) - 9

55 - 9

DE = 46

Therefore, the value of DE is 46

User AMacK
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21 votes
21 votes

Question:

DF= 78, DE = 5x -9, EF = 2x + 10, find DE.

Solution:

First, solve for the value of x.

  • DE + EF = DF
  • (5x - 9) + (2x + 10) = 78
  • 7x + 1 = 78
  • 7x = 78 - 1
  • 7x = 77/7
  • x = 11

Then, plug and substitute the value of x to find the DE.

  • DE
  • 5x - 9
  • 5(11) - 9
  • 55 - 9
  • 46

Answer:

  • The value of DE is 46
User ReadyFreddy
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