5(a). 8 inches
5(b). 9 and 3/4, or 9.75 inches
5(c). 6.5 centimeters
5(d). 1 and 1/2, or 1.5 inches
5. x = 4
6. No, they are not collinear. If they were collinear, AB + BC would have to equal the value of AC.
7 + 4 does not equal 9, so the points are not perfectly aligned with each other (collinear)