 Okay, so this problem is asking us, well if we have a car that has a fuel economy of 12.8 kilometers per liter and we have 22.5 gallons in the thing, how far can it drive, okay? So this is again a series of conversions where we're converting gallons to miles, oh yeah, the distance they want is in miles. So we're going to use a couple of conversion factors. One is given to you by the problem, the rate at which the fuel is burned, the 12.8 kilometers per liter. Hopefully by now you can look at that and say, oh yeah, I see that can be used as a conversion factor. The other two are the gallons to liters and the kilometers to miles that I gave you up there and we'll just go through it. So distance is going to be, well you start with 22.5 gallons, we want to convert that to liters so we can cancel out our gallons and then now that we have liters, we can use that fuel economy to cancel out the liters, giving us a distance in kilometers but we don't want it in kilometers, we want it in miles so we'll use our other conversion factor to go from kilometers to miles, canceling out kilometers. So now we have to ask ourselves, well the calculator gives me a bunch of numbers after the decimal, what is the number of sig figs? Well I go and look at the constants given by the problem and I see that they both have three sig figs so my answer has to go to three sig figs. So the final answer is going to be 677 miles. Okay, hopefully that makes sense.