What is the cost of gasolin to drive a car on a 300 mile trip?
1. in 1980 it cost $7.90 to take a 300 mile trip by car.
2. The price of gasoline has tripled since 1980.
St. 1: Was the cost just for gasoline, or did the $7.90 include other costs as well? Insuff.
St. 2: Insuff.
Combined: Still insuff, so E
. Unless $7.90 is the cost of gasoline alone, then C