you can find slope by doing y=mx+b the y intercept is 8 (b) so you would do y=mx+8 so now you add in a y and x to the equation, so just take any coordinate on the line like 1,5 i think it is? I can't really see the picture lol. but then you'd plug in 5=m1+8 and it looks to end up being 5=(-3)1+8. Hope this helps!