Question

Two angles are supplementary angles and the larger is 20° less than three times the smaller. find the anglea

Answer 1

Heya Dear !
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the sum of two supplementary angles is 180 degrees 
Let the smaller angles be x 
It is given that large angle is 20 less than 3 times of smaller i.e = 3x - 20 
ATQ 
x + 3x - 20 = 180 
4x - 20 = 180 
4(x-5)  = 180 
x - 5     = 45 
x          = 50
3x - 20 = 130 
SO smaller angle = 50°
and larger angle  = 130°
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Answer 2

HI !

Let the smaller angle be "x" , and larger angle be "y"

then ,

as they are supplementary , their angle   sum = 180°

x + y = 180 ----> (1)

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also , 

larger angle is 20 less than three times the smaller angle !

y = 3x - 20

3x - y = 20             ----> (2) 

Adding equations 1 and 2 ,

x + y = 180
3x -y = 20
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4x = 200

x = 200/4

x = 50

x +y = 180

y = 180 - 50 = 130

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The angles are 50° and 130°