12000m/hr to mi/hr solve plzz

Which one ? is the answer and how to find this answer

Which expression do you get when you eliminate the negative exponents of 4a^2 b^216a^-3 b

The evening newspaper is delivered at a random time between 5: 30 and 6: 30 pm. dinner is at a random time between 6: 00 and 7: 00 pm. each spinner is spun 30 times and the newspaper arrived 19 times before dinner. determine the experimental probability of the newspaper arriving before dinner.