Answer:
65
Step-by-step explanation:
The sum of the measures of the angles of a triangle equals 180°.
3x + 40 + m<1 = 180
3x + m<1 = 140
<1 and the angle measuring 5x - 10 are supplementary angles, so the sum of their measure is 180°.
m<1 + 5x - 10 = 180
Solve for m<1 and substitute in equation above.
m<1 = 190 - 5x
3x + 190 - 5x = 140
-2x = -50
x = 25
m<1 = 190 - 5x
m<1 = 190 - 5(25)
m<1 = 190 - 125
m<1 = 65
