ok so she used 355 miles using 17 gallons all we have to know now is how many gallons for one mile so 335/17=1/x that's the formula.
So (17x10)/355=0.04788...gallon's a mile
0.04788....x284= 13.6 gallons
THE ANSWER IS 13.6 GALLONS OF GAS
hope this helped :)