Answer:
36 + 18 = 54 miles or 18*3 = 54 miles
Step-by-step explanation:
If 18 miles is 1/3 of the road then there are 2/3 of the road left. 2/3 is twice as big as 1/3, And so what is left is
18*2= 36 miles left.
The total length of his drive is 36 miles +18 miles = 54 miles