Question

OB is the bisector of AD and EC. . EO = 2x – 20 and OC = 70 – x. Solve for x.

Answer 1

We know that OB bisects EC where they intersect would be at point O, 
so the two lengths EO and OC must be equal. 

2x - 20 = 70 - x 

[adding x + 20 to each side] 

2x - 20 + x + 20 = 70 - x + x + 20

[simplifying]

3x = 90 

[dividing each side by 3]

x = 30 would be the answer