Answer:
For statement
, the reason is Definition of slope.
and for statement
, the reason is Triangle A is similar to triangle B.
Step-by-step explanation:
If slope of triangles are equal than Triangle A is similar to triangle B.
so, in statement
when we simplify
we get

then the reason for this statement is "If slope of triangles are equal"
And the definition of slope in general is 
so, for the statement
, the reason is Definition of slope.