Answer:
m<4 = 66°
Explanation:
m<1 = 8x + 7
m<2 = 4x + 14
m<3 = ?
m<4 = 13x + 12
m<3 and m<4 are supplementary angle which mean they add up to 180°, linearly.
m<3 + m<4 = 180°
These three angle are in a triangle that add up to 180°
m<1 + m<2 + m<3 = 180°
m<3 + m<4 = 180° => m<4 = 180° - m<3
m<1 + m<2 = 180° - m<3
m<1 + m<2 = m<4
(8x + 7) + (4x + 14) = (13x + 12)
(8x + 4x) + (7 + 14) = 13x + 12
12x + 21 = 13x + 12
21 - 12 = 13x - 12x
9 = x
Substitute x = 9 to find the degree for m<4.
m<4 = 13x + 12
m<4 = 13*(4) + 12
m<4 = 13x + 1254 + 12 = 66°