Answer:
Step-by-step explanation:
First, subtract 180 and "12x-3", which equals 180-12x+3
Then add 46, "5x+7", and "180-12x+3"
46+5x+7+180-12x+3 = 180
Since the degrees in a triangle add up to 180 degrees, cancel out the 180 degrees from this side "180-12x+3" and the other side "180"
46+5x+7-12x+3=0
46+10-7x=0
56=7x
X = 8
