I think it's B. 168 units
Because I multiplied them all together and halved the answer
1 hour = 60 minutes
5 x 60 = 300
300 + 45 = 345
391 miles/345 min = 1.13 miles per min
1.13 x (60 min/1 mile) = 67.8 miles per hour
Ashley drove ~67.8 miles per hour
hope this helps
I think the missing number should be
12.87
The numerator is 72 and the denominator is 2. 72/2