Answer:
4x+2x-12+4x+42.
ALL interior angles of a triangle ADD up to 180 degrees.
4x+2x-12+4x+42 = 180
add LIKE terms
10x+30 = 180
subtract 30 from both sides
10x = 150
divide both sides by 10
x = 15
Step-by-step explanation:
the choice A = 15
[tex]4x + (4x + 42) + (2x - 12) = 180 \\ \\ 4x + 4x + 2x + 42 - 12 = 180 \\ 10x + 30 = 180 \\ 10x = 180 - 30 \\ 10x = 150 \\ \\ x = \frac{150}{10} \\ \\ x = 15[/tex]
I hope I helped you^_^
