Question

M 2 = 2x°, m 3 = 5x°, m 1 = 2x + 5x 5x - 2x 180 - 5x 180 - 7x

Answer 1

We know: the sum of measures of triangle angles is 180°.

Therefore we have the equation

$m\angle1+m\angle2+m\angle3=180^o\to m\angle1=180^o-m\angle2-m\angle3$

Substitute $m\angle2=2x,\ m\angle3=5x$:

$m\angle1=180-2x-5x=180-7x$

Answer: 180 - 7x