Answer:
Step-by-step explanation:
If points A, B and C are collinear, then A, B and C lies on the same straight line. Hence AB+BC = AC
Given
AB = 12''
BC = 8''
To get length od segment AC, we will substitute the given values into the formula above as shown;
AB+BC = AC
12 + 8 =AC
AC = 12+ 8
AC = 20''
Hence the length of AC is 20''