Answer:

Step-by-step explanation:
Given,
Total distance = 120 miles,
Here x represents Bob's speed on the first half of the trip( 60 miles ).

So, the time taken in first half = 
Now, He drove an average of 1.2 times faster on the second half than first half,
⇒ His speed in second half = 1.2 x,
So, the time taken in second half = 
Hence, the total time taken by him = the time taken in first half + the time taken in second half





Which is the required expression.