Hey there!
8x - 3 + 4x + 3 = 180°
COMBINE the LIKE TERMS
(8x + 4x) - (3 + 3) = 180°
8x + 4x - 3 + 3 = 180°
12x + 0 = 180°
12x = 180°
DIVIDE 12 to BOTH SIDES
12x/12 = 180/12
CANCEL out: 12/12 because that gives you 1
KEEP: 180/12 because it helps solve for the x-value
NEW EQUATION: x = 180/12
SIMPLIFY IT!
x = 15
Therefore, your overall answer is: x = 15
The answer to your given question is:
12x + 0 = 180
Good luck on your assignment & enjoy your day!
~Amphitrite1040:)