5:30pm
just add 30 mins to 4:15pm which is 4:45pm then add the 45 mins to that which becomes 5:30pm
This is the simplest proportion i have seen.
This is how we do it:

=

The answer surprisingly is obvious,
z = 1But we can still do cross multiplication
7z = 7
Divide by 7 to isolate z

7 and 7 cancels out
z = 1

The plane can travel 1530km in

hours.
As you can see in the picture below, it's not possible to create a triangle that has side lengths of 4, 8, and 3
triangle inequality theorem, impossible triangle
It turns out that there are some rules about the side lengths of triangles. You can't just make up 3 random numbers and have a triangle! You could end up with 3 lines like those pictured above that cannot be connected to form a triangle.