Remember that a segment that connects two points A and B is written as:
AB
Now, assuming that in this case the points B, D, and C are collinear, we can see that C is between B and D.
With this, we can find that BC = 10
Then we can write:
BD = BC + CD
And we know that:
BD = 14
CD = 4
we can replace thest two in the above equation to get:
14 = BC + 4
14 - 4 = BC
10 = BC
We just found that the value of the segment BC is 10.
If you want to learn more, you can read:
https://brainly.com/question/18171498
