Notice how there is a dash bisecting every line of this triangle. Also keep in mind that the interior angles of any triangle add up to 180°. BEcause there is a dash on each line it is using SSS criterion and showing us that all the side lengths are the same length.
Therefore this is an equilateral triangle. The angles and side lengths of an equilateral triangle are the sane. Therefore every angle in this triangle will be 60°. IN support of this, the 3 angles of 60° add up to 180 meaning this is a valid answer.
So if the m<2=x+69, to get 60 (the measure of all angles) x has to be -9
