Question

If lines $AB,CD,EF$ all intersects at one point, then the value of $n$ is:

• A. $30$
• B. $40$
• C. $50$
• D. $60$

Answer 1

The correct option is B $40$

The lines are intersect at one point, so the opposite side of the angle is equal to the other side.
Consider $\angle AOC={70}^o$, then $\angle BOD={70}^o$
Then from the straight line $EF$, we can find the value of $n$ as the straight line to the sum of the angle $={180}^o$
So, ${70}^o+{70}^o+n={180}^o$
$\Rightarrow {140}^o+n={180}^o$
$\Rightarrow n={40}^o$