Answer:
10
Step-by-step explanation:
I think is 10 because they are different triangles but both with the same measure, as you can see both angles are the same [36] and both sides of the triangle too [6] so when you divide the base [20] by 2 , 20÷2=10
the first one is equivalent : Adding property is applied
the second one is not equivalent.
5/9
i got it right
B is correct