Answer:
Relation 3 is a function and Relation 4 is nog
You can calculate the difference/vector of both points:

then calculate the magnitude/length like pythagoras
25% of the class likes mint gum, 5% likes orange, 20% likes raspberry lemonade, of the remaining % likes cherry. how much is the remaining % of students?
3x + 4y = 16 Write original equation
3x + 4y - 4y = -4y + 16 Subtract 4y from each side
3x = -4y +16 Simplify
3x/3 = -4y/3 + 16/3 Divide each side by three
x = -4y/3 +16/3 Simplify
I hope this helps!