Answer:
Similarity ratio is

Step-by-step explanation:
Assume that:
The first triangle is ABC where:
AB = 4 units, BC = 6 units and AC = 10 units
The second triangle is DEF where:
DE = 6 units, EF = 9 units and DF = 15 units
Now, we are given that the two triangles are similar, this means that the corresponding sides are similar.
Therefore:
similarity ratio =

Now, we substitute with the values given and simplify any of them to get the similarity ratio as follows:
similarity ratio:
=

Hope this helps :)