Please help with function rule

X Y
-7 -1
-4 -3
-1 -5
2 7
5 -9
Thank you

every time x changes by +3, y changes by -2

except for that +7 which I suspect is a typo
slope of this straight line is therefore -2/3
so the function is of form
y = (-2/3) x + b
put in any old point to get b
-1 = (-2/3)(-7) + b
-1 = 14/3 + b

b = -14/3 - 3/3 = -17/3
so
y = (-2/3) x - 17/3
3 y = -2 x -17