I believe the answer is 8
Answer:
38 mpg
Step-by-step explanation:
Initial efficiency = 39 mpg
Initial speed = 40 mph
Final speed = 50 mph
The efficiency drop between 40 mph and 50 mph is given by:

The total efficiency drop from 40 to 50 mph is:

Therefore, the efficiency at 50 mph is:

(5•4)-8 the answer is 12 because 5 times 4 is 20. Then 20 minus 8 is 12.
From left to right it’s 1, 49, 9, 70