6+1ty is the best thing to do with this
if the diameter is 15, its radius is half that, or 7.5
I'm not sure how you obtained -5 as your answer but this is the mathematical explanation. hope this helps!
So the difference of speed will be 25-17 = 8 mph the last one choice
hope helped
The answer is 7 7/8 because 5 1/4 times 1 1/2 is 7 7/8. I hope this answers your question.