Answer:
28
Explanation:
Alright, if <1 = <3, then:
5x + 8 = 12x - 20
so we'll simplify and move the x's and the numbers to different sides:
8 + 20 = 12x - 5x
now simplify using algebra:
28 = 7x
divide 28 by 7:
x = 4
m<1 = m3
plug 4 in as 'x' and you get 28.
m<1 = m<3 = m<2 because they're opposite angles on different sides of a 180-degree line.
m<2 = 28