Answer:
The last graph.
Step-by-step explanation:
In the first graph, the darker triangle has one side that is 1/3 of the corresponding side of the other triangle, and one side that is 2/5 of the corresponding side of the other triangle. This is not proportional for all sides, so this is not a dilation.
In the second graph, the darker triangle has one side that is 1/2 of the corresponding side of the other triangle, and one side that is 3/5 of the corresponding side of the other triangle. This is not proportional for all sides, so this is not a dilation.
In the third graph, the darker triangle has one side that is 1/3 of the corresponding side of the other triangle, and one side that is 1/2 of the corresponding side of the other triangle. This is not proportional for all sides, so this is not a dilation.
In the fourth graph, the darker triangle has one side that is 2/3 of the corresponding side of he other triangle, and another side that is 4/6=2/3 of the corresponding side of the other triangle. Since these are both right triangles, this means the other side, the hypotenuse, will have the same ratio. Since it is proportional for all sides, this is a dilation.
by 
. The first thing we do is make common denominators for 
. Now we add 
by 
: 
. Now we make 
a mixed number:
. Therefore, your answer is 
. Hoped I helped. :)