If ab=51, bc=10, and ad=100, solve for cd

Question

Its on a number line but i cant seems to find the answer can someone help me please 

Answer 1

You have a single line segment (ad) that is divided into 3 other segments.  I will draw them for you so you can visualize.

 

 

|------------------------------------------------------------------------|

a                                                                                            d

 

 

|------------|---|-------------------------------------------------------|

a               b   c                                                                       d

 

 

 

The top illustration represents the entire line.  The bottom illustration represents the line broken up into several segments.  Using this illustration, we can create an equation for the sum of the segments.

 

ab + bc + cd = ad

 

 

Solve for cd from this equation.