number 13 it's geometry

Mathematics
Tutor: None Selected Time limit: 1 Day

Oct 6th, 2015

Thank you for the opportunity to help you with your question!

Any two adjacent angles ( that is, two angles next to each other) will make a straight angle. 

A straight angle = 180 degrees.

So               4y + 17y -9 = 180

                     21y -9 = 180                   (because 4y + 17y = 21y)

Add 9 to both sides:

                     21y + 9 -9 = 180 + 9

                      21y = 189

Divide both sides by 21

21y ÷ 21 = 189 ÷ 21

y = 9

Similarly  5x +1 + 21x -3 = 180

                 26 x -2 = 182      (note 5x + 21x = 26x and 1 -3 = -2)

add 2 to both sides

26x + 2 -2 = 2 + 180

26x = 182

divide both sides by 26

26x ÷ 26 = 182 ÷ 26

x = 7

Please let me know if you need any clarification. I'm always happy to answer your questions.
Oct 6th, 2015

slight error for second part

Similarly  5x +1 + 21x -3 = 180

                 26 x -2 = 180     (note 5x + 21x = 26x and 1 -3 = -2)

add 2 to both sides

26x + 2 -2 = 2 + 180

26x = 182

divide both sides by 26

26x ÷ 26 = 182 ÷ 26

x = 7


Oct 6th, 2015

thank you so much

Oct 6th, 2015

Your welcome. 

Oct 6th, 2015

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