From the condition, the weight of 1 gallon of fuel is 

w =  = 5.5 pounds.


Now, to answer the question, we need to add the weight of (58-42) = 16 gallons of fuel to the weight of the plane 
carrying 42 gallons of fuel, 2331 pounds.


So, the answer is 2331 + 16*5.5 = 2419 pounds.