Answer: y= -3x
(there is no y-intercept in the points you listed so if you can find one on a picture of your question, do so. but since i do not see a given y-intercept, i assume it is 0)
To find the slope, use the two points given.
1st: subtract the y-values. 0-6= -6.
2nd: subtract the x-values. 0-(-2)= 2
3rd: you have -6/2.
4th: simplify to get a slope of -3.