First, you may set up a proportion of a number of mi/hr = a number of mi/hr. Hence, you may write 325/13 = x mi/9. Multiply numerators and denominators of opposite fractions to get (325)(9) = 13x. Thus, simplify 2925 = 13x by dividing both sides of the EQ by 13 to isolate the variable you're solving for. You should get your final answer.
