Question 290257
First you have the x and y backwards.
x (a) is acres and y (s) is snakes
(9,2) and (12, 9)
so s=ma+b
But first we have to find the slope
(y-y)/(x-x)=m
or in this case 
(s-s)/(a-a)=m
(9-2)/(12-9)=7/3=m
7/3=m
s=(7/3)*a+b
now plug in either point
2=(7/3)*9+b
2=63/3+b
2=21+b
-19=b
s=7a/3-19
3s=7a-57
The closest answer is c
3s-7a-57
I think you copied - for =
Double check your answer options
Perhaps you copied them wrong.