The ab segment equation is

X=-3 where -1≤y≤6

Point b lies on line X+Y=0

The point of intersecton is x=-3 ,y=3

The line segment is divided into two parts and its length is measured on Y axis

First part of divided segment =3-(-1)=4

Second part of divided segment =6-3=3

Point p divides the line 3:4 =3/4 :1