The equation is simple, you just have to reason the sentence, the quotient of a number, this means that the result of the division is 3.5, and the number has to be divided by 6, so the equation would end up looiking like this:
As 6 is dividing and you want to clear N, you just put it on the other side of the equation multiplying, and you end up with this:
7% is 0.07 because it mean per hundred. .15 is next because when you divide 4/25 you get 0.16 so yeah then 4/25 is third then .28 is last because it is the greatest.