you take your x variables and compare them to each other and compare them to the y variables. each x variable goes into the y variable 2 times. thats where the 2(x) comes from. then once yiu do that for all your x variables, you must look to see what they have in common. in this case all of them are one digit less than the y value. so you add that to your equation and it become ' 2(x) + 1 = y '
