An x+y value question......HELP!!?

Question

I know how to easily find an unknown formula for a set of x and y values.

EX:

x=|1 |2 |3 |4 |5 |200|

y=|12|15|18|21|23|???|

I know that the formula could be x(#it increase)+ random number

So I could keep punching in numbers on my calculator to find that "random number".

And the random number is nine.

y=x(3)+9

y=200(3)+9

???=609

My teacher says that the number shows in the chart.

I don't want to keep on punching in numbers until i get it right.

So WHERE is this random number?????

How can I find it?

Answer 1

I think this is what she's getting at:

x=|1 |2 |3 |4 |5 |200|

y=|12|15|18|21|23|???|

3x=|3| 6| 9| 12|15|600

D=| 9| 9| 9|  9|  9|  9

Where D is the difference between y and 3x

_/