1) Sketching it
Since the line segment AD = 10x -5 and AC= 3x +1 and CD= 15
According to the Segment Addition postulate we can write:
3x+1+15=10x-5 <em>Combining like terms</em>
3x +16 = 10x -5 <em>Subtract 16 from both sides</em>
3x = 10x-5-16 Subtract 10x from both sides
3x-10x =-21
-7x = -21
7x=21 <em>Dividing by 7 on both sides</em>
x=3
