Answer:
The solution for x that I got is 7.6.
When substituted for x for the two equations, the angle measures are:
86, 38.4, and 55.6.
86 degrees is the largest angle measure.
12a)
5x + 45 + 3x - 25 = 180
8x + 20 = 180
8x = 160
x = 20
12b)
2x - 5 = 2(20) - 5 = 40 - 5 = 35
3x - 25 = 3(20) - 25 = 60 - 25 = 35
y = 180 - (35+35)
y = 180 - 70
y = 110