In exercise 3 (2,6) means that x=2 and y=6 so you have to check that if this values of x and y satisfied the given equation, by showing that the left hand side = the right hand side ..
So you already know the difference between the new number and original number, so all you have to do now is plug it in to this: Percentage Change=Difference/Original Number x100. So 17.99/257=.07x100 which equals 7%. So B is the correct answer.
