How you would do this would be finding the slope of the two position at for example you would y2-y1/x2-x1 which in this case would be 4-(-5)/1-(-2)=9/3 which makes the slope 3 and then you 3 times x which is the mx +b =y form then when you try to find the y value you do 3 times 1 which is 3 and you find out that b would be -8 so your equation would be 3x-8=y
