Answer:
0.1 seconds
Step-by-step explanation:
10/100=0.1
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
the easiest way I find a midpoint of two points is the midpoint theorem, here it is:

For x and y plug in the two coordinates given, (4,-4) & (0,8)
so once you plug the numbers into the equation you would get:
(2,2)