Answer:
x is 28
Step-by-step explanation:
When two lines intersected in a point, then they formed two pairs of vertically opposite angles. The vertically opposite angles are equal in measures
Let us solve our question
∵ AB and CD are straight lines intersected at O
∴ ∠AOC and ∠DOB are vertically opposite angles
∴ ∠AOD and ∠COB are vertically opposite angles
→ The vertically opposite angles are equal in measures
∴ m∠AOC = m∠DOB
∴ m∠COB = m∠AOD
→ ∠ COB is formed from ∠COE, ∠EOF, and ∠FOB
∵ m∠COB = m∠COE + m∠EOF + m∠FOB
∵ m∠COE = 3x, m∠EOF = x, m∠FOB = x + 12
∴ m∠COB = 3x + x + x + 12
→ Add the like terms
∴ m∠COB = 5x + 12
∵ m∠AOD = 152°
∵ m∠COB = m∠AOD
∴ 5x + 12 = 152
→ Subtract 12 from both sides
∴ 5x + 12 - 12 = 152 - 12
∴ 5x = 140
→ Divide both sides by 5
∴ [tex]\frac{5x}{5}=\frac{140}{5}[/tex]
∴ x = 28
→ To justify the solution substitute x by 28 in m∠COB the answer must
be 152°
∵ m∠COB = 5x + 12
∵ x = 28
∴ m∠COB = 5(28) + 12
∴ m∠COB = 140 + 12
∴ m∠COB = 152°
∴ The value of x is correct
