360 miles traveled on 12 gallons of gasoline

If we have to find the unit rate then we first determine which is independent and which is dependent, Becuase a number of miles depending on how much gas we have. So, 12 is x and 360 is y. We must write a ratio. 360:12, this can be also written as 360/12 which is 30. So, one gallon of gasoline can last 30 miles. 

First subtract 10 from both side
y^2+6y-16=0
(y+8)(y-2)=0
-8 and 2

Using the rise/run rule. you would get 2/6.simp. 1/3