Answer:
I believe it is 5
Step-by-step explanation:
Since the triangles are of the same proportions, we can use ratios. AC and AB represent the same side. Putting the smaller numbers on top, AB/AC = BD/CE. 4/12 = BD/15. Cross multiply. 12BD = 60. Simplify. 12/12 BD = 60/12. BD= 5. I hope that helped.
