Question

I am supposed to find the equation for the boundary lines, using the points 0,4 and 3,5. I got 5-4/3-0, which plugged into y=mx+b would equal y=1/3x+b. The book says b equals four, but where does this number come from? Thanks!

Answer 1

Since y = (1/3)x + b, and
y = 4 when x = 0,
4 = (1/3)*0 + b
b = 4