SOLUTION: One-fifth of the supplement of an angle is 9 degrees less than twice the complement of the angle. Find the measure of the supplement of the angle in degrees.

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Question 1173619: One-fifth of the supplement of an angle is 9 degrees less than twice the complement of the angle. Find the measure of the supplement of the angle in degrees.
Found 2 solutions by ewatrrr, ikleyn:
Answer by ewatrrr(24785)   (Show Source): You can put this solution on YOUR website!
 
Hi,
One-fifth of the supplement of an angle(x) is 9 degrees less than twice the complement of the angle(x).
Letting x represent the angle
Write as You Read:
Hitting the = sign at the 'is' as is usually the case
(1/5)(180° -x)= -9 + 2(90°-x)
(180° -x)= -45 + 10(90°-x)
180-x = -45 + 900- 10x
9x = 665
x = 75°
checking our answer:
(1/5)(180° -x)= -9 + 2(90°-x)
(1/5)(180° -75)= -9 + 2(90°-75)
21 = -9 + 30 checks.
Wish You the Best in your Studies.

Answer by ikleyn(52802)   (Show Source): You can put this solution on YOUR website!
.


            The solution by @ewatrrr is  INCORRECT.   She  READ  the problem incorrectly -

            THERFORE,  her first equation is incorrect,  producing errors to the very end.

            I came to bring you the correct solution.


Solution

Let x be the angle measure in degrees.


Then the supplement is (180-x);  one-fifth of the supplement is    and

     the complement is  (90-x) degrees.


THEREFORE, your equation is


     = 2*(90-x) - 9


Multiply both sides by 5 and simplify


    180 - x = 10*(90-x) - 45

    180 - x = 900 - 10x - 45

    10x - x = 900 - 45 - 180

       9x   = 675

        x   = 675/9 = 75.


ANSWER.  The angle is 75 degrees.


CHECK.   Supplement is 105 degrees.  One-fifth of supplement is 105/5 = 21 degrees; complement is 15 degrees 

         and twice the complement is 30 degrees.  Finally,  21 degrees is 9 degrees less than 30 degrees.   ! Correct !

Solved.

==============

To learn about supplementary / complementary angles,  read the lessons
    - Angles basics
    - HOW TO solve problems on supplementary, complementary or vertical angles - Examples
in this site.


Consider these lessons as your handbook,  textbook,  guide,  tutorials and  (free of charge)  home teacher.


. . . . . . . .

@ewatrrr fixed her post after seeing my solution.



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