Question

Which one is correct ?

Answer 1

Give the two exterior angles of 133 and 142, we can deduce that the interior angles are 47 and 38, respectively. In fact, if $i$ and $e$ are the interior and exterior angles, respectively, we have

$i=180-e$

Now, the interior angles of a triangle sum up to 180 degrees. Since we already have angles of 47 and 38 degrees, the missing angle is

$180-47-38=95$

Which implies

$n=180-95=85$