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If x+5 and 4x-15 are complementary angles, find the value of x. 

 Dec 3, 2018

Best Answer 

 #4
avatar
+1

Complementary angles sum to 90°

 

x + 5 + 4x - 15 =  90

 

5x - 10 = 90      add 10 to both sides

 

5x = 100           divide by 5

 

x = 20

 

Credit to CPhill

He is the best

 Dec 3, 2018
 #1
avatar+98172 
+2

Complementary angles sum to 90°

 

x + 5 + 4x - 15 =  90

 

5x - 10 = 90      add 10 to both sides

 

5x = 100           divide by 5

 

x = 20

 

Thanks to tertre for spotting my stupid error....!!!

 

 

cool cool cool

 Dec 3, 2018
edited by CPhill  Dec 3, 2018
 #2
avatar+3994 
+2

@CPhill, isn't it 5x=100, x=20?

tertre  Dec 3, 2018
 #3
avatar+98172 
+1

Thanks, tertre....that's what I get for watching football and trying to do math at the same time...I'll make the correction....!!!

 

cool cool cool

CPhill  Dec 3, 2018
 #5
avatar+3994 
+2

Lol! It's okay, I'm watching football, too!

tertre  Dec 3, 2018
 #4
avatar
+1
Best Answer

Complementary angles sum to 90°

 

x + 5 + 4x - 15 =  90

 

5x - 10 = 90      add 10 to both sides

 

5x = 100           divide by 5

 

x = 20

 

Credit to CPhill

He is the best

Guest Dec 3, 2018
 #6
avatar+601 
+1

Yeah he is!

CoolStuffYT  Dec 3, 2018
 #7
avatar+601 
+2

If they are complementary angles, then x+5+4x-15=90

5x-10=90

5x=100

x=20

The value of x is 20.

(i was too lazy to do LaTeX lol)

 

You are very welcome!

:P

 Dec 3, 2018

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