I would use grams, because in my country watermelons are small, but if they were huge I would use kilograms
I think the best figure for a cereal box would be a cylinder. There are no corners on a cylinder where it is hard to fit round pieces of cereal into. The formula for the surface area of the cylinder is 2*pi*r*h+2*pi*r^2. The formula for the volume of the cylinder is pi*r^2*h. (Then I would add some more info supporting why you think a cylinder would make a good box.)
Start by finding 7% of the $23.20:
Now add this to $23.20:
Now, let's find 18% of this new total with tax to find the tip amount:
This is the tip amount. And finally, let's add this to the 24.824:
Not sure if you were given any instructions about rounding, but Ana's cost will be around $29.29.
Hope this helps.
Answer:
Yes ,0.3434434443 is a rational number.