Question 58537
You got the slope right, but when you substituted your point and slope into the slope intercept form to find b, you put the x coordinate where the y goes and the y coordinate where the x goes.  m=-4, (x,y)=(2,-1)
-1=(-4)(2)+b
-1=-8+b
8-1=8-8+b
7=b
{{{highlight(y=-4x+7)}}} 
If you want to check your answer, use the other point (5,-13) to see if it's =.
-13=-4(5)+7
-13=-20+7
-13=-13  Looks like we're right!
Happy Calculating!!!