Question

The points A, O and B are collinear points. Find the value of x in the following diagrams.

Answer 1

In each case the given angles are on a line, hence their sum should be 180°

(1)→2x+10+3x-10+40=180
→5x+40=180
→5x=140
→x=28

(2)→28+x+90+36=180
→x+154=180
→x=26

Hope my ans was easy for u

Answer 2

Heya Dear !
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1) here 

2x + 10 + 3x- 10 +40 = 180 [LPA's]
5x + 40                      = 180 
5(x+8)                        = 180 
x+ 8                           = 36 
x                                = 28 °

2.
28 + x + 36+ 90 = 180 [LPA's]
154 + x      = 180 
 x                = 26°