So a line is 180°
Since it gave you options, the easiest way would be to plug it in (plug and chug)
the answer is 11
first what I did was plug 12 into 5x+10 and then found the answer and then added 58°
the answer of that subtracted from 180
with that I then plugged in 11 for x for 11x+2 = 123
180 - 123 = 57 which is the same answer for the missing angle within the triangle
