Since slope is y=mx+b and m is -3 you would plug in the (5,1) which 5 is x and 1 is y. you would plug them into the y=mx+b and then u would get 1= -3(5) +b and then it would go into 1= -15 +b then -15 would move to the other side and b=16
Hoped this helped! :)
