Answer:
A; 10
Step-by-step explanation:
What we can see here is that the triangles are similar.
Hence, the ratio of their sides are equivalent.
Thus, mathematically;
ED/BA = DF/AC = BC/EF
what we want to calculate is ED = x
Thus;
x/15 = 12/18
Cross multiply;
18 * x = 12 * 15
18x = 180
x = 180/18
x = 10
