Thank you for the opportunity to help you with your question!
This question wants to guide you through setting up a proportion, which is two fractions that are equal to each other.
You need to decide if you want kilometers or liters to be in the numerator of the fraction. It doesn't matter which one you pick. Most people say kilometers per liter, so you could put the kilometers in the numerator.
The the blank boxes you have would say this:
Then you would fill in the spaces for the fractions. You don't know how many kilometers you could go on 115 liters of gas, so you put an x there in the fraction.
450 km X km
------------- = -------------
225 liters 115 liters
Then you would cross multiply:
450 * 115 = 225 * X
Figure out what 450* 115 is. It's 51,750. So
51,750 = 225 * X
You need to figure out what number multiplied by 225 is 51,750.
So you should divide 51,570 by 225 (or you might be used to saying "divide by 225 on both sides of the equation).
51,750 divided by 225 is 230.
So X = 230, which means the boat can travel 230 kilometers on 115 liters of gas.
I hope this helps you move forward on the problem! Let me know if you need any more clarification!