Answer: 20.2 mph
Step-by-step explanation:
Given
Train travels 10.1 miles in half an hour i.e.
Distance 
time 
we know, 
Insert the values

You would do
51-5= 46
then you would divide
46/2= 23
so Susan is
23+5=28
Susan is 28 years old and her sister is 23
28+23=51
5) Obtuse triangle because the top angle is more than 90 degrees
Your answer would be D.
Make this the brainliest answer if it helped!